usertype now respects factory functions and does not make default constructors/destructors unless the compiler says its okay
new and __gc functions can be overridden for usertypes to provide handle-like creation and deletion functions
Overloading match fixes
RAII improvements for all usertypes
Added tests to make sure these features stay
additional tests to make sure pass-by-value and copy semantics work as intended
new proxy_base class to reduce code duplication
update function / protected_function usage (to solve starwing's issue while keeping code as clean as possible)
function result is meant to be transient, and therefore should not be regularly storeable by the user... but there is no way to make a "and you can't have anything but a temporary to this" type, as far as I can tell.
checkargs is now properly propogated through the "call" functions
tests now define SOL_CHECK_ARGUMENTS to make sure
the tests will always check arguments now as well (caught one minor implementation detail missing from that!)
sol::object had a few reference leaks in the way it retrieved values: it now does it properly without leaving the stack at +1 item
sol::stack was drastically cleaned up, with the following key change:
* sol::stack::push now returns an integer of the number of things its pushed (usually 1, but can be more) (Thanks, @PrincessNyanara!)
* sol::stack::call now calls functions flexibly, and getting is done more reliably
* due to the innovation of stack::call and using absolute indices, we no longer have to use reverse_call style programming to deal with lua
* sol::reference::get_type is now const-correct
* sol::state and sol::table now have a cleaned up `get` implementation since it is no longer held back by the ugliness of VC++'s incapability to handle templates
* the name `sol::userdata` now belongs to a type that actually encapsualtes a void* with a pusher/getter than gets a userdata void* value (TODO: give it a template to make it static_cast to that type on get?)
* lightuserdata_t -> light_userdata, upvalue_t -> upvalue as type names (mostly details)
* pushers for various types were updated to return integers
