Merge pull request #63 from abhinavsood/reserved_taxonomy_names

WordPress reserved terms
Small changes; syntax
Error message only in admin
Sprintf for taxonomy translations
Field::save
Better 'checked' check for checkboxes
Merge branch 'better-classes'
Version 1.6.2
Extended properties
Javascript bugs fixed; Checked check improved
Version 1.6.3
Box description
Version 1.6.4
Again better OOP
Docs for output method
OOP for tabs
Version 1.6.5
Bug fix for attached existing taxonomies to post types
Version 1.6.6
Deprecated Cuztom_Radio; Better reserved term notices