Update endians.nim

adds swapEndian16 function
Update os.nim

added file/dirExists synonyms for existsFile/dir
Define $ operator for TRune
Define $ operator for TRune
Koch now uses PATH/nimrod correctly
Add info about twitter and bootstrapping from github to website.
Rename C sources dir to c_code.
added test cases from strange loop event
bugfix: doc generation for actors.nim works again
Merge pull request #779 from brihat/master

Define $ operator for TRune
Merge pull request #777 from fowlmouth/patch-4

Update os.nim
Merge pull request #812 from girvo/koch-fix

Koch now uses $PATH/nimrod correctly
Merge pull request #775 from fowlmouth/patch-3

Update endians.nim
master compiler compiles with devel
Optimized the size of PNG images. 172KB > 143KB

Used optpng + pngout + deflopt.
Merge pull request #839 from ReneSac/master

Optimized the size of PNG images. 172KB > 143KB