Another mega commit... loadsof restructure, and a pretty good one! :)

- changed the BIF_DrawString() function. it used to work different for
  AA fonts  as for default fonts. Now it's identical. Setting color for fonts
  can just be done with OpenGL, for both font types.
  Removed: BIF_DrawStringRGB()
- added theme color options for Buttons
- recoded DefButton, so it automatically chooses the right color.
- had to remove a 1000 uiBlockSetCol() calls for that reason...
- uiBlockSetCol() still works, to override automatic color

- removed entirely the silly old color system (BIFColorID). All color
  calls can now be done with a BIF_ThemeColor() call, including fonts and
  buttons and opengl stuff

- all buttons in button header have headercolor by default

- recoded drawing icons, it was a really bad & old loop doing manually
  colorshading and blending... which was per pixel a load of code!
  Now it uses a single OpenGL call to blend or colorize. Quite faster!
- (as test, for review) icons don't colorize anymore with button color,
  but have a different alpha to blend in (when not active)


- recoded the entire interface_draw.c file...:
- drawing buttons is separated in three parts:
  1. main drawing function for text and icons
  2. free definable callback for button itself
  3. free definable callback for slider
- removed a load of redundant code for this!
- coded a minimal theme, and adjusted Matt's buttons to match new
  callback system

- adding new drawing themes is piece of cake now
- for coders, default 'themes' to be aware of:
  UI_EMBOSS : the themable drawing style
  UI_EMBOSSP: the pulldown menu system (apart from color not themable)
  UI_EMBOSSN: draw nothing, only text and/or icon
  UI_EMBOSSM: minimal theme, still in use for Logic and Constraintsa
  this can be set with uiBlockSetEmboss(block) or in the uiNewBlock() call.

TODO: make UI API call for button alignment

(plus removed another series of warnings from code...)

Plus: fixed bug in Matts commit: he used a 'short' button for an 'int'

source/blender/src/header_imasel.c

@@ -106,8 +106,10 @@ void imasel_buttons(void)
 	simasel= curarea->spacedata.first;
 
 	sprintf(naam, "header %d", curarea->headwin);
-	block= uiNewBlock(&curarea->uiblocks, naam, UI_EMBOSSX, UI_HELV, curarea->headwin);
-	uiBlockSetCol(block, BUTBLUE);
+	block= uiNewBlock(&curarea->uiblocks, naam, UI_EMBOSS, UI_HELV, curarea->headwin);
+
+	if(area_is_active_area(curarea)) uiBlockSetCol(block, TH_HEADER);
+	else uiBlockSetCol(block, TH_HEADERDESEL);
 
 	curarea->butspacetype= SPACE_IMASEL;