syntax_sensitive Swaps Key Bindings

Previously, setting `syntax_sensitive` to true would switch the key binding for ctrl+h to a syntax-sensitive search. However, it would leave ctrl+alt+h alone, leaving you with two ways to do a syntax-sensitive search, but no way to search globally. With this change, setting `syntax_sensitive` to true instead swaps the bindings, thus allowing you to perform a global search with the alternate key combination.