Merge pull request #4 from gsvgit/master

Fix l-attributes.
Subgraphs support has been added
Interface for users has been created
Examples of usage have been added
Some cosmetical fixes
Allow restore nuget packages on build/
Merge https://github.com/octomarat/DotParser

Conflicts:
	DotParserProject/DotParserProject/DotGrammar.yrd
	DotParserProject/DotParserProject/DotParser.fs
	DotParserProject/DotParserProject/DotParserProject.fsproj
	DotParserProject/DotParserProject/Program.fs
Rm FSharp.PowerPack