Removed extern declaration of static dmx-protocol variables.
Init dmx-protocol state machine in init-function.
Add 'const' to set_dmx_channels parameter, rename parameter to a more meaningful name.
Fixed some typos
Fix index error in set_dmx_channels
Add support for a starting index in set_dmx_channels.
Merge pull request #328 from tu500/dmx

A few DMX bugfixes