Add a pkg-config module for RtMidi.
Fix rtmidi-config.in (test uses = for string comparison, not ==)
Update version numbers.
Add install/uninstall targets.
Add prefix to output of rtmidi-config.
Make a symbolic link for the major version.
Merge pull request #1 from radarsat1/master

Fix rtmidi-config, add install/uninstall targets, support --prefix.