renderer: set draw colors on texture correctly
add some window/renderer diagnostics
correct include paths
These only worked accidentally because the SDL2 directory was linked to
/usr/local/include. Now they work using sdl2-config.
Render help items in such a way.
Disable the cursor while the menu is focussed.
Menubar selection movement.
Focus the menubar when alt is pressed.
Mouse cursor acting like QBasic's aaaaaaa
Render an immediate, too.
CORERCT SCROLLBAR BEHAIVOUR
Parameterise the editor size.
Start working toward multiple editing windows.
Pretty-print binary ops better.