See details.

- Storing the poster id in database instead of re-computing the id each
time.
- Added multiple image resizing modes.
- Added seperate thumbnail generation methode for png and other images
since png need the transparency, and other don't ( except gif, which i
will adress  it later ).
- Updated SQL database schema and the WPost class to support posterID
field.
- Added BumpLimit variable.
- Removed uncessary HTML codes escapes.
- Removed old comments from GlobalFunction file.
- Fixed a bug in the GetThreads function.