improve auto indent

[ThomasSevestre]

This PR improves auto indent behavior.

For instance, when typing def my_func + ENTER

We get :

def my_func
  |  <--- cursor position

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[ThomasSevestre]

@cla-bot check

[cla-bot]

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[ThomasSevestre]

@cla-bot check

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[vitallium]

@ThomasSevestre Looks awesome! I have just one question about removing some keywords from fallback (tweak) regex patterns. Thanks!