Prettify tk dumping
Filter out comments in lexer already, if wanted

So there won't ever be TK_COMMENTs generated if comments aren't wanted to
be preserved. This is also nice for the preparsing step which doesn't need
comments and can just completely ignore them this way.
Re-add/improve comment preservation
Replace hRemoveOuterDIVIDERs(): Don't emit empty lines at BOF/EOF

DIVIDERs may hold comments, so it's no good to remove them.
Re-add AST nodes for #if/#endif etc. for test cases without ppEval()
pp: Don't try to evaluate / or % BOPs if it's a divison by zero
Restructure tests
Start *.fbfrog preset file parser
Improve "expected but found" error reports
Let LEXMODE_FBFROG use all keywords, because it needs KW_UNDEF

KW_UNDEF is part of C/FB shared keywords, so using FB-only + fbfrog-only
keywords isn't enough for *.fbfrog syntax.
*.fbfrog: Fix empty line parsing
*.fbfrog: Add COPYFILE command
*.fbfrog: Add REMOVE command
Move libpng/libzip data into presets