Blender Git Loki

BLF: initial word-wrap support

- Adds support for word wrapping to Blender's BLF font library.
- Splits lines when width limit is reached or on explicit n newlines.

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).