Avoid processing columns if there aren't any to allow empty tables.
fixes #2532134 Added sort test to cover Date, Number and String data types with case sensitive sort available by setting a caseSensitive param to true on the table column.
ref #2532134 Changed Y.Lang.isString() to typeof() === 'string' to improve performance, and added comment to component history.
ref #2532134 Updated documentation with new caseSensitive attribute details. Updated default order of test data.
ref #2532134 Updated documentation added a short paragraph to the 'Column sorting' section
Merge branch 'master' of git://github.com/yui/yui3
Merge remote-tracking branch 'upstream/master'
pass stringified data to custom transport layer
Fallback to default attribute values when invalid values are used.

When an `ATTRS` setter returns `Y.Attribute.INVALID_VALUE` during
initialization, and a default attribute value is defined, fallback to
that value.

Fixes #2528732
Add more tests for Attribute default value fallback.
Merge branch 'live-docs' of github.com:yui/yui3 into live-docs
fix argument name
Fix #2531914
Create unit test to (dis)prove #2531914.
Merge branch 'dev-master' of github.com:yui/yui3 into dt-2531914
Build Datatable.
Removed erroneous build files.
Merge branch 'attr-init-val' into dev-master

Conflicts:
	src/attribute/HISTORY.md
Build Attribute.
Update "Basic Caching" example to escape user input.