New port: audio/avldrums-lv2: Dedicated AVLDrumkits LV2 Plugin

LV2 plugin that converts MIDI signals to drums audio.
Full description and video tutorial:
http://x42-plugins.com/x42/x42-avldrums

Submitted by: myself
Approved by: adamw (mentor)
Differential Revision: https://reviews.freebsd.org/D14183