Handle vSpacing when tracking headers. Fixes #12.

Any positive vertical space is supported. However, only small values of
negative vertical spacing will work. The size of the value that will
work is relative to the size of the header rows and those surrounding
them.
Add get for stickied header. Related to #13.
Also reset stickied header id on reset. Fixes #15.
Regen simple hdr list on data invalid. Fixes #16.
Measure sticky header. Fixes #14.
Pass correct size to headers on measure call. #14.
Ensure stickied header was measured. Fixes #14.
Ensure headers have layout parameters. Fixes #17.
Made mDelegate private and added getter
Merge pull request #19 from bjerva/master

Hide wrapped adapter and provide access via getter.
Change to Jar Library Format.

This change is to ease distribution and development using this library.
However the change requires all configuration to be programmatic, so
setting behaviour in an XML layout is no longer possible.
Merge changes for Jar Library support. Closes #21.
Cleanup unused elements.
Cleanup unused code.
Respect IGNORE_ITEM_VIEW_TYPE.
Merge changes to Fix #22.
Merge cleanup of unused code and files. Closes #20.
Add missing references in maven POM.
Update README for changes to Jar Library.
Add roadmap to readme.