implemented VectorUtils.union()

Change-Id: Ida43141a592c7baa7bc5825a167fd19c745158b8
externalReload() now waits for the user to approve local storage access
and displays an error message when the user denies access. Previously,
session history would be lost.

Change-Id: I90630c373302dcf05ff5d2b3bc62bf1b389184a3
moved checkbox to the left

Change-Id: Iaa9dadd320810447289d2d8b0c8b2c3493370e95
JavaScript API now supports integer indexing for ILinkableHashMap
children in paths.

Change-Id: Ic48a1082658f4612f1cf37ac27e196ae9f4ca14d
convertRecordsToRows() now stores missing values as "" instead of null.

Change-Id: Ie40769e4a44da7f26635e2476c36f6c48f39a6a6
Fixed bug where CSVDataSourceEditor's append file feature wouldn't add
new columns.

Change-Id: Iec4636ee2fcc9e8f55cac6d3132f26f08cac71ed