Fix #2049(columnDef): don't change user-provided column def

Also includes capability for columns to be dynamically set to
visible and not visible with a callback provided so that the grid
will give effect to that.  Refer tutorial 113.
Merge pull request #2056 from PaulL1/columnDefs

Fix #2049(columnDef): don't change user-provided column def
Merge pull request #2054 from novice3030/master

RTL support for column resize feature
Fix #2042 (pinning): Pinning column menu item duplication on resize
Merge pull request #2064 from mathiasdose/Issue#2042

Fix #2042 (pinning): Pinning column menu item duplication on resize
Release v3.0.0-rc.15
Fix pinning column menu item duplication when i18n, update i18n zh-cn.js and zh-tw.js
Compare pinning menu item by name property.
Merge pull request #2068 from cxr29/master

Fix pinning column menu item duplication when i18n, update i18n zh-cn.js and zh-tw.js.