Rename DateTime trait to Datetime trait

[midhun-pm]

Fixes #811

[codecov-io]

Codecov Report

Merging #814 into master will increase coverage by 0.28%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##           master     #814      +/-   ##
==========================================
+ Coverage   72.13%   72.41%   +0.28%     
==========================================
  Files          51       51              
  Lines        6363     6363              
  Branches     1274     1274              
==========================================
+ Hits         4590     4608      +18     
+ Misses       1383     1362      -21     
- Partials      390      393       +3

Impacted Files	Coverage Δ
traits/api.py	90.32% <ø> (ø)	⬆️
traits/editor_factories.py	81.25% <0%> (ø)	⬆️
traits/trait_types.py	69.73% <100%> (-0.17%)	⬇️
traits/traits.py	76.92% <0%> (+4.04%)	⬆️
traits/etsconfig/etsconfig.py	63.8% <0%> (+6.13%)	⬆️

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[mdickinson]

There are a couple of DateTimes persisting in the source:

(traits) mirzakhani:traits mdickinson$ grin "\bDateTime\b"
./traits/editor_factories.py:
  173 :     editing DateTime values.
./traits/trait_types.py:
 3591 : # -- DateTime Trait definition ------------------------------------------------

Apart from that, looks good.

[mdickinson]

A couple of missed DateTimes (already commented); apart from that, LGTM.

I'm assuming that we'll rename DateTimeEditor separately (probably in a pair of PRs against Traits and TraitsUI).

[mdickinson]

LGTM