The reason is to be conservative with the API. However, less used functions, such as xpath_vec_bool(), xpath_vec_ctx() and xpath_vec_flag() are changed with a new `nsc`parameter, which should be set to NULL in most cases.
* Added regex cache to type resolution
* Added compiled regexp parameter as part of internal yang type resolution functions
* All internal `ys_populate_*()` functions (except ys_populate()) have switched parameters: `clicon_handle, yang_stmt *)`
* New xmldb_get1() returning actual cache - not a copy. This has lead to some householding instead of just deleting the copy
* xml_diff rewritten to work linearly instead of O(2)
* New xml_insert function using tree search. The new code uses this in insertion xmldb_put and defaults. (Note previous xml_insert renamed to xml_wrap_all)