Create a "bitmap" text system in render.c that is shared by X and SDL.
Implemented line drawing (for mono underline) on the canvas. The text
cursor and underlining now go through the remapper on X. Remove
scaling from the previously used X calls (impossible with X fonts).
Screen updates now lock the surface during the whole update for SDL;
the SDL code pushes rectangles to be updated and sends them in one go.
Mode changes need to be checked before locking the surface: moved the
mode adjust calls out of the common update code.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@1641 7758b857-130e-0410-ab9c-d8735a528d18