Fixed a bug that sometimes made write chunks in the region file header.

parse_header() now updates the file size before parsing the header
making possible to call it after modifiying the region file.

Now the header is updated everytime the region file is modified.
Merge pull request #67 from Fenixin/fix

Fixed a bug that sometimes made write chunks in the region file header.
Merge remote-tracking branch 'twoolie/master'
Add Travis testing for Python 3.3
Recommend Pillow instead of PIL library
Minor fix: allow trailing slash in folder names.
Support for Python 3 for map.py
Fix file-closed test for Python 2.6