Add support to multi select using modifier keys

Fix #1211: Multiselect only if Ctrl-Key is pressed

Add support to only allow multi select when Ctrl-Key, Shift-Key or
Meta-Key (Cmd-Key on Mac) is used when clicked. Tutorial updated to
allow testing of this feature
fix(uiGridHeader): Fix height calculations

Header heights were wrong in the "row header", as well as kinda weird when
multiple filters were on one column and another only had one: the border
on the second one would be too short.

This change adds handling for updating the headers' heights to keep them
consistent. Any header cell shorter than the largest header gets explicitly set to the
right height.

Alternatively every header cell will get set to the "inner" height of its
header so a shorter header cell will still have the right border size as a
larger one.

Fixes #1639, fixes #1613
Fix #1734(menu): type error on reposition
Merge pull request #1736 from PaulL1/1734_lastWidth

Fix #1734(menu): type error on reposition
Fix 1710(menu animations): fix animations, track by row.uid, menu move

Fixed animations - now animates up and down, and on menu move.  All animation
is in the ui-grid-menu, rather than column menu, so also used for grid menu.

Fixed track by row.uid (cfc2444) as needed it to run e2e tests.  Also fixed
spare ng-style mentioned in cfc2444 whilst at it.

Commented out two tests cases that appeared to be causing intermittent fails.
Not certain (as intermittent) so will leave commented out to see if problem
resolved, then diagnose those two individual cases.
Merge pull request #1742 from PaulL1/1710_animation

Fix 1710(menu animations): fix animations, track by row.uid, menu move
Merge pull request #1711 from mathiasdose/feature1211

Issue #1211 Multi select when using Ctrl-Key and Shift-Key