Added parsing and output of dependency graph

* parses Dependency.txt style files
* Outputs graphviz, or flat text
* as suggested by feature:
    BlueBrain#6

utils/efel_graph_dependency

@@ -0,0 +1,142 @@
+#!/usr/bin/env python
+'''graph the dependency graph'''
+
+import argparse
+import logging
+import os
+
+from collections import namedtuple, defaultdict
+
+Feature = namedtuple('Feature', 'library name dependencies')
+Dependency = namedtuple('Dependency', 'feature wildcard')
+
+
+def create_feature(line):
+    '''Convert a line from the Dependency.txt to a feature
+
+    LibV2:AP_duration_half_width_change	#LibV2:AP_duration_half_width
+    LibV2:E6	#LibV1:AP_amplitude;APWaveForm
+    '''
+    tokenized_line = line.strip().split()
+
+    library, name = '', tokenized_line[0]
+    if ':' in name:
+        library, name = name.strip().split(':')
+
+    dependencies = []
+    if len(tokenized_line) > 1:
+        dependencies.extend(create_dependency(d) for d in tokenized_line[1:])
+
+    return Feature(library=library, name=name, dependencies=dependencies)
+
+
+def create_dependency(line):
+    '''parse a dependency, and create a Dependency'''
+    line = line.strip()
+    assert line[0] == '#', '"%s": Not a feature dependency, must start w/ #' % line
+    feature, wildcard = line[1:], ''
+    if ';' in feature:
+        feature, wildcard = feature.split(';')
+    return Dependency(feature=feature, wildcard=wildcard)
+
+
+def get_feature_library(dependency_file):
+    '''parse the `dependency_file` and gather all the features and their dependencies'''
+    feature_library = defaultdict(dict)
+    with open(dependency_file) as fd:
+        for line in fd:
+            feature = create_feature(line)
+            feature_library[feature.library][feature.name] = feature
+            #  defaults are the last to be loaded
+            feature_library['Default'][feature.name] = feature
+
+    def find_feature(dependency):
+        '''find the feature in the current feature_library'''
+        if ':' in dependency.feature:
+            library, name = dependency.feature.split(':')
+        else:
+            library, name = 'Default', dependency.feature
+        feature = feature_library[library][name]
+        return Dependency(feature=feature, wildcard=dependency.wildcard)
+
+    #  resolve features pointers
+    for library in feature_library.keys():
+        if 'Default' == library:
+            continue
+        for feature in feature_library[library].values():
+            for i in range(len(feature.dependencies)):
+                feature.dependencies[i] = find_feature(feature.dependencies[i])
+
+    return feature_library
+
+
+COLORS = ('blue', 'crimson', 'forestgreen', 'dodgerblue3', 'aquamarine4',
+          )
+
+
+def output_graphivz(feature_library, filename, draw_dependencies=False,
+                    output_dot=False):
+    '''create a PNG at filename of the dependencies'''
+    try:
+        import pygraphviz
+    except ImportError:
+        import sys
+        sys.exit('Need to have the "pygraphviz" package installed')
+    G = pygraphviz.AGraph(name='Dependencies', directed=True)
+    G.graph_attr['overlap'] = 'false'
+    G.graph_attr['rankdir'] = 'TB'
+
+    for library, color in zip(sorted(feature_library.keys()), COLORS):
+        if 'Default' == library:
+            continue
+        G.add_node(library, shape='circle', color=color)
+        sg = G.add_subgraph(name=library, style="")
+        for name, feature in feature_library[library].iteritems():
+            full_name = library + ':' + name
+            sg.add_node(full_name, label=name, shape='box', color=color)
+            sg.add_edge(library, full_name, color=color)
+            if draw_dependencies:
+                for dep in feature.dependencies:
+                    target = dep.feature.library + ':' + dep.feature.name
+                    G.add_edge(full_name, target, color='yellowgreen')
+
+    if output_dot:
+        G.write(os.path.splitext(filename)[0] + '.dot')
+    G.draw(filename, prog='dot')
+
+
+def get_parser():
+    '''return the argument parser'''
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('-i', '--input', required=True,
+                        help='Input Dependency.txt file')
+    parser.add_argument('-g', '--graph',
+                        help='Output graph png file location')
+    parser.add_argument('--graph-deps', action='store_true',
+                        help='If graphing, draw the links to the dependencies')
+    parser.add_argument('--dot', action='store_true',
+                        help='If graphing, output the dot file')
+    parser.add_argument('-d', '--dump', action='store_true',
+                        help='Dump the resolved dependency tree')
+    parser.add_argument('-v', '--verbose', action='count', default=0,
+                        help='-v for INFO, -vv for DEBUG')
+    return parser
+
+
+def main(args):
+    '''main'''
+    logging.basicConfig(level=(
+        logging.WARNING, logging.INFO, logging.DEBUG)[min(args.verbose, 2)])
+
+    feature_library = get_feature_library(args.input)
+    if args.dump:
+        from pprint import pprint
+        pprint(dict(feature_library))
+    if args.graph:
+        output_graphivz(feature_library, args.graph, args.graph_deps, args.dot)
+
+
+if __name__ == '__main__':
+    PARSER = get_parser()
+    main(PARSER.parse_args())