This CL fixes the following compiler warnings.

- Indirect access to static member
- Access to a non-accessible member of an enclosing type
- Parameter assignment
- Method can be static
- Local variable declaration hides another field or variable
- Value of local variable is not used
- Unused import
- Unused private member
- Unnecessary 'else' statement
- Unnecessary declaration of throw exception
- Redundant type arguments
- Missing '@Override' annotation
- Unused '@SuppressWarning' annotations

Bug: 18003991
Change-Id: Icfebe753e53a2cc621848f769d6a3d7ce501ebc7

This is a groundwork to attach LocaleSpan for committed text
in LatinIME.

This CL adds a utility method to ensure that a given range
of the text is coverted by at most one LocaleSpan.  Of course
it could be possible to allow a substring to be coverted by
multiple LocaleSpans at the same time, but ensuring uniqueness
for LocaleSpan is supposed to be a good starting point.

BUG: 16029304
Change-Id: Ic33a7178d0df1f05d3626aeb5773ec902254703f

This is a groundwork for enabling LocaleSpan support.
LocaleSpan is available in API Level 17 and later. We need some
abstraction layer as usual.

BUG: 16029304
Change-Id: Iead1afdc540216edb1b17f91a40d9edb2e790168