Directory control

These routines access, modify, and obtain information about the directory structure.

Directory-control routines

Routine	Use
`_chdir`, `_wchdir`	Change current working directory
`_chdrive`	Change current drive
`_getcwd`, `_wgetcwd`	Get current working directory for default drive
`_getdcwd`, `_wgetdcwd`	Get current working directory for specified drive
`_getdiskfree`	Populates a `_diskfree_t` structure with information about a disk drive.
`_getdrive`	Get current (default) drive
`_getdrives`	Returns a bitmask representing the currently available disk drives.
`_mkdir`, `_wmkdir`	Make new directory
`_rmdir`, `_wrmdir`	Remove directory
`_searchenv`, `_wsearchenv`, `_searchenv_s`, `_wsearchenv_s`	Search for given file on specified paths