REFACTORING: Rename Item Type enums
DOUBLE, INT, etc are reserved keywords on Windows. DataBrowser,
which is an application using SMTK as a library would fail to build on
Windows due to this issue. This MR appends an Type
to them and
rewrites them in camel case.
This's CMB side MR. SMTK MR's SHA is 662b0cfbacfe82b244bbc84509907baf444f80a5.