Remaining string_* functions are deprecated

[nwellnhof]

The string_* functions have been deprecated for a while. The remaining functions are:

string_make
string_ord
string_chr
string_to_cstring_nullable
string_max_bytes
string_increment

string_make should be replaced with Parrot_str_new_init. You can use Parrot_find_encoding to get an encoding from a cstring.

Replace string_ord with Parrot_str_indexed.

Replace string_chr with Parrot_str_chr.

Replace string_to_cstring_nullable with Parrot_str_to_cstring.

string_max_bytes and string_increment will be removed.

[nwellnhof]

Branch nwellnhof/string_unescape contains some preliminary work.

[nwellnhof]

Removed the functions in commit b8b3c7db92.