import collections as originial networkx.algorithms.simple_cycles does
allow user to specify output dotfile.dot to write current graph, fragment, or subgraph to dot file. this will NOT overwrite existing dot files as user may extend dot file in same directory
indicate dotfile when calling gratelpy_draw to write dot file of entire graph
output critical fragment and subgraphs of critical fragment of example 4 as dot files
Adapted drawing Example 4 (reversible subtstrate inhibition) to Dot output
Adapted single-layer MAPK system drawing to Dot output
Added function that outputs supplied graph as dot file.
improved drawing function, outputs .dot and .pdf from .dot, accepts node positions, accepts duplicate node positions and merges corresponding nodes into one
outputs .dot graph for each critical fragment together with constitutent subgraphs
also outputs .dot graph of entire graph
argument handling improved with argparse package
Merge branch 'create-pygraphviz-dot'

Conflicts:
	draw_example_4.py
	draw_single_layer_mapk.py
Merge branch 'master' of github.com:waltherg/gratelpy