Context-dependent patterns

[laughedelic]

Instead of just pairs, I want to be able to define patterns.

• matching context around the cursor with regexes (left/right)
• surrounding cursor with arbitrary text (multi-character symbol-pairs)
• several pattern-pairs per trigger, i.e. different pairs depending on the context pattens which are bound to the same key (trigger)

One thing that I'm not sure about here is the way to store these new settings so that they are easy to change for a user and easy to parse for the plugin "_

[laughedelic]

This POC implementation worked, but something got outdated. Once I have a bit more time I will update it and merge.