[AD] al_font_textprintf() and uvszprintf()

[Evert Glebbeek <eglebbk@xxxxxxxxxx>]

Currently, al_font_textprintf() allocates a static buffer of size 512  
characters. While I'm sure that's plenty for any line of text anyone  
is likely to want to display on a monitor in ASCII on a current  
monitor, it's an arbitrary limit and it's probably not particularly  
safe when having unicode output. Should this be increased? Or better  
yet, a way found to increase the size of the buffer dynamically as  
needed?

Secondly, it uses uvszprintf(), which is fine in principle, but  
uvszprintf() is an Allegro function that is missing the al_ prefix.  
Should it acquire one? I can think of reasons why maybe it shouldn't,  
but it does seem to violate A5's intention of not polluting the  
global namespace.

Evert