Build the antlr runtime during our own build instead of providing prebuilt binaries in the src tree

This means getting rid of the bat and sh files to create this, and do it directly in cmake.

The current msclibrary/CMakeLists.txt has this list of files created by ANTLR:

set(ANTLR_SRC parser/MscBaseVisitor.h parser/MscLexer.h parser/MscParser.h parser/MscVisitor.h parser/MscBaseVisitor.cpp parser/MscLexer.cpp parser/MscParser.cpp parser/MscVisitor.cpp )

These should be placed in the build directory, not in the source directory.

And the files should be removed from the .gitignore.