Merge pull request #3 from rpspringuel/master

More Engine Updates
Bugfix to gregoriosyms.sty

The gregoriosyms style (which provides access to the special characters defined by gregoriotex without loading the score setting overhead) wasn't working as written.  The following changes have fixed that on my system:

1) gregoriotex-symbols.tex followed the OpenType Font loader code of luaotfload for naming the symbol font.  Thus, said package needs to be loaded in order for it to work.

2) gregoriotex-symbols.tex checks its version for compatibility with gregoriotex.  Since gregoriotex is not loaded when using gregoriosyms.sty, I needed to create a dummy command to bypass the version check.