Some macros defined by wasysym.sty work only in text mode: They either
produce an error in math mode, or wrong output. These symbols are now marked
as text symbols, so that no \ensuremath is created for LaTeX export if they
appear inside \text{}, and the correct images are created.
development/tools/generate_symbols_images.py now checks for each symbol in
lib/symbols whether its image is listed in lib/Makefile.am and whether it has
a toolbar entry in lib/ui/stdtoolbars.inc.
