• regexp_x functions should be immutable

fix dbms_random.string

• this function should be VOLATILE
• the generated strings can contains chars \ and ~

• fix partially broken compatibility (corner case) of instr function

• WIN32 only: use MoveFileEx() function instead replace(). It allows overwrite file by function dbms_file.rename()

• fix infinity recursion when Orafce is loaded by shared_preload_libraries on PostgreSQL 15

full use file wide char API on WIN32 platform. It allows to use non ascii chars inside filenames on MS WIN.

• fix win32 build

fix build for Postgres 15

• implementation oracle.sys_guid
• WIN32: encode filename to wide char string, and use _wfopen function instead fopen - it allows
  to use non ascii chars in file names.

• fix regress test, issue #193