Formatting changes.

CodeMaid cleanup and updated formatting of Doxygen comments.
Added headers to MSVC project.
Added const to lo_set_plugin_position param.

Doesn't affect usage, just a safety thing for implementation.
Added stdbool.h workaround for MSVC < 2013.
Misc fixes caught by cppcheck.

Fixed compile error, and GetMasters always returning an empty vector.