Extend action target with "Track" dropdown to choose optionally selectable track

[helgoboss]

Many actions in REAPER use the currently selected as their context. Currently you would need 2 mappings in ReaLearn to select a track and execute an action on it but this change could make it just one! More convenience.

[helgoboss]

Mmh, actually not as many useful actions that work on selected tracks as I thought ... making this low prio.

[helgoboss]

Maybe there are more actions that could benefit from this feature than immediately obvious. E.g. ""Track: Cycle folder collapsed state" - which works on the currently selected track although the name doesn't directly suggest it. Raised prio again because that's a quick win.