• Adds support for word wrapping to Blender's BLF font library.
• Splits lines when width limit is reached or on explicit \n newlines.
• Tooltips wrap all text automatically (when it exceeds the default tooltip width).

IMHO this patch is ready for master.

Further work:

• Currently drawing into off-screen pixel buffers (render stamp for eg). doesn't support word-wrapping, (not hard to support though).
• Later on we could have wrapping for text labels if we want (though we'd need to ensure this works properly with the layout-engine).

As a test this patch makes the render button have a very long tooltip.

API details.

• Word wrapping is used when BLF_WORD_WRAP flag is enabled.
• There is a single loop to handle line wrapping, this runs callback, passing in a substring, this way we can avoid code-duplication for all word-wrapped versions of functions... OR... avoid having to add support for word-wrapping directly into each function.
• The ResultBLF struct was added to be able to get the number of wrapped lines, when calling otherwise unrelated functions such as BLF_draw/BLF_width/BLF_boundbox, which can be passed as the last argument to BLF_*_ex() functions.
• The ResultBLF struct is used to store the result of drawing (currently only the number of lines wrapped, and the width).