Label color picker: give color picker in addition to defaults

[damithc]

The default color pallet is still useful. May be we can give our color picker in addition to the existing one

[damithc]

In fact I prefer to remove this feature for now, until we have a fully-baked feature dealing with label colors

[jiajunGit]

@damithc I have temporarily disabled the color picker in commit ee4bf74

[damithc]

Noted. Let me close this for now. Can reopen later if needed.