Rename FPID to LIB_ID as is now used as a generic library identifier and
is no longer specific to footprints.
Remove all mention of footprint from the new LIB_ID doxygen comments and
code.
Rename files fpid.h and fpid.cpp to lib_id.h and lib_id.cpp.
Rename fp_lib_table.keywords file to lib_table.keywords and adjust CMake
build dependencies accordingly.
Update all source files effected by the code and file name changes.
Update .gitignore for file name changes.