Add gfx_get_string_width()
First pass for gfx_draw_string()
Second pass of gfx_draw_string. Still buggy
Fix some bugs, tidy up

Still buggy...
gfx_draw_string complete. Needs tidying
Fix use of g1_elements and tidy comments
Fix bug in gfx_get_string_width
draw_string_centred
Add address for common string format buffer
More string functions
Start of clip_text
Tidy up loop on pointer
clip text mostly working
Finish clip string
Rename variables in get_width to align with clip_string
Fix some pointer issues
String functions for wrapped text
Replace pad_0E with zoom_level
Merge pull request #162 from ZedThree/gfx_strings

Gfx strings