[Trivial] Fixing samples

Under samples/ :
- Added a 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
- More verbose message in case of unrecognized token.

Also, I discovered that d2html.d doesn't support the '$' token, which makes :
make; for i in `ls -1 *.d`; do echo "Processing $i..."; ./d2html $i; done
Fails on 3 samples.