Rename hmnt symbols to hmn for consistency

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Add His Master's Noise MegaArps effect parser

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Rename med and hmn synth to extras

Change name of extra handlers from synth to extra to avoid ambiguity with
Adlib and Spectrum synths, which use a totally different structure.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Add His Master's Noise MegaArp tables

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Rename MED extras symbols for consistency

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>