click and double click behaviour to mimic excel

[cldougl]

in order to have behaviour be consistent with excel:

• on single click: remove current content and overwrite with new content
• on double click: add cursor and append (currently prepends) to content

right now we have the reverse: single click prepends content and double click overwrites

[charleyferrari]

Also see #66

[Marc-Andre-Rivet]

@cldougl This is the best I've got so far:
-> single click: focuses on the input and selects all content
-> click a second time to insert at a specific position

[cldougl]

@anocella you can see the suggested behaviour above.

[anocella]

This looks promising.

[Marc-Andre-Rivet]

In PR #79

[cldougl]

PR #79 improved the behaviour- leaving this open as further discussion is needed on how to apply a proper double click event rather than a click click event.

[chriddyp]

Closing in favor of #174