scripts/mutool_draw.py: improve use of global state.
scripts/mutool_draw.py: improve use of global state.

Previously fns had to be careful to do 'global foo' if modifying a global,
which was fragile and lead to a number of bugs. Now all global state is within
a 'state' object, and code does 'state.foo = ...'.

This fixes issue with the <oi> variable.

Also fixed handing of -f option.

sebras/mupdf,ArtifexSoftware/mupdf,ccxvii/mupdf,sebras/mupdf,TamirEvan/mupdf,sebras/mupdf,TamirEvan/mupdf,ccxvii/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,TamirEvan/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,sebras/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,ccxvii/mupdf,TamirEvan/mupdf,ccxvii/mupdf,ccxvii/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ccxvii/mupdf,TamirEvan/mupdf,TamirEvan/mupdf,sebras/mupdf,ArtifexSoftware/mupdf,sebras/mupdf