Image filepath using real filename

Change image filepath to use real filename. It's using os.path.basename(). 
It should be okay on Linux because Blender always adapt it's path string depend on the os.
Fix for packed images with no filename.
Merge branch 'ucupumar-master'
When unpacking a texture show the color format.
Warn the user if the image format set in the Render panel and used to
unpack images (save_render) does not match the texture filename extension.
Avoid Techniques folder by default
Merge pull request #38 from fooflare/master

Avoid Techniques folder by default
Set default Techniques folder name.
Added a button for restoring the default paths.
Added a confirm dialog on the revert buttons.