Various fix/improvement to samples:
- Adding gitignore
- Added a sample GNU Makefile for linux compilation
- Fixed infinite loop on hexa/octal numbers in d2html.d
- Fixed 64 bits issues (int used) on listener.d and htmlget.d
TODO: Fix d2html.d to support the '$' token
Renamed Makefile to posix.mak and fixed indent according to CR
Merge pull request #2640 from Geod24/master

[Trivial] Fixing samples