128 channel support with user feedback

[firthm01]

Supercedes #253 - same fixes + additional commits for user feedback when channel limits are exceeded on import

[firthm01]

Code review notes;

General approach was to make everything support 128 channels under the hood. Some areas needed to know the actual supported channels of the DAW (e.g, for routing during import and for UI), so there were some helper funcs for that.

Tasks

• Add a global #define to set the channel count - change all hard-coded channel counts to use this. For routing, we need to know exactly how many channels the DAW supports so we don't use out-of-range values (e.g, REAPER older than v7). This is done with helper functions.
  main...aa10ba2

• UI changes:

  • Decided to list channels up to the maximum, but to just disable unsupported ones in the dropdown - this required some changes to the EarComboBox* classes to support disabling entries
    aa10ba2...f15d61d
  • Show an icon and a tooltip if not all channels are available. For DS plugin, this required widening the left column and recentring the meters afterwards.
    2768bc0...935f83c

• User feedback when problems occur during import;

  • ImportListener (and so ImportBroadcaster) supports warnings. A little crude using just a string, but didn't think it was worth over-engineering it at this stage. Keeps counts of warnings rather than storing dupes.
    935f83c...1623858
  • ImportStatus::COMPLETE state was handled in the import dialog timer method so was ran repeatedly. Moved it so it only runs once (onStateChanged)
    1623858...6fd222d
  • ImportBroadcaster ptr passed to the PluginSuite classes at the start of import so they can pass back warnings - warns about channels and also about unsupported PFs. Warnings displayed in import dialog.
    6fd222d...c3d70d0

• (slightly unrelated) Show a more helpful error message when you try to import non-ADM - came across this during testing
  f15d61d...2768bc0

[firthm01]

Suggestions implemented. Diff since last review; b2ec02f...a7d37bc

[firthm01]

Closes #244