Optimized and refactored fm_get_directorysize() function

[michael-milette]

Also added validation.

[michael-milette]

Also added validation in addition to optimizing and refactoring the fm_get_directorysize() function.

While the performance increase on Linux is only about 3%, it is 20% to 25% on Windows when tested on a directory structure containing 44,381 files and 12,618 folders for a total of about
2.1 GB.

Notes:

• The function no longer ever returns 'Folder'. This is unnecessary as 'Quick output' mode is handled before the function call.
• Testing for directory vs files is not required since we are now skipping dots.
• The function returns 0 if the directory does not exist.

Let me know if you have any questions or concerns.

Best regards,

Michael Milette

[michael-milette]

Thank you @michael-milette !