Add custom upper<->lowercase translation tables for better localization support.

Translation tables by Henrik Holst.
replace CreateDirA() and mkdir() scattered everywhere by createDir() with some more error checking.
Fix build on linux
Move scripts to files, to make automated overriding easier
Update README
Create screenshots dir on startup, if necessary
Display error if mod downloader failed to rename temp file
Add option to hideInGameMenu() to cancel the options menu if it's active.
Replace A* pathfinding with much faster jump point search.

This also fixes entities glithing through walls, as diagonal cracks
were assumed walkable.
Little optimization for molestPath()
Should actually upload the file in question...
Lua API stuff:

+ isScriptedEntity()
+ findPath()
+ castLine()
- fix off by one in isObstructedBlock() (lower+rightmost row/col missing)
vcproj update
Fix linux/osx build
Fix OSX build with SDL1.2 (nasty, nasty)
Fix linux build, once more, now for real
Add Lua functions (+ related text class changes):

- text_getHeight()
- getUserInputString()
Reload stringbank on map editor map reload
Lua API: Setter/getter for gravity
Fix animation editor problems: Undo buffer memory hoarding, add warning if saving failed.

Thanks to Peri for finally making me fix this.