Add Selection addition and subtraction feature and keybinding
This MR improves selection as the title showed also it fixes S
key
shortcut to trigger selection. Shift+ left
mouse would trigger
selection addition and Ctrl + left
mouse would trigger selection
subtraction. Escape
key would clear all the selections.
Default camera settings are also updated.
SMTK corresponding commit 706ebe9ed3e4704dc53aa2c6132395d20dc65d6c.