This reduces the total number of khash_t instantiations from 22 to 8.
Make the khash internal functions take the size of values as a runtime
parameter. This is abstracted with typesafe Map containers which
are still specialized for both key, value type.
Introduce `Set(key)` type for when there is no value.
Refactor shada.c to use Map/Set instead of khash directly.
This requires `map_ref` operation to be more flexible.
Return pointers to both key and value, plus an indicator for new_item.
As a bonus, `map_key` is now redundant.
Instead of Map(cstr_t, FileMarks), use a pointer map as the FileMarks struct is
humongous.
Make `event_strings` actually work like an intern pool instead of wtf it
was doing before.
libnvim couldn't be easily used in C++ due to the use of reserved keywords.
Additionally, add explicit casts to *alloc function calls used in inline
functions, as C++ doesn't allow implicit casts from void pointers.
