fix file encoding and missing "\" after directory

[tmplinshi]

• Change file encoding from UTF-8 (Without BOM) to UTF-8 (With BOM), because of the use of unicode colon character ꞉. AHK V2 seems can handle no-BOM file, but AHK V1 can't.
• Change all of directory . to directory . "\" .

[iseahound]

I don't think this does what you want, because now simple functions like ImagePutFile(0) fail due to the extra backslash.

Suggestions:

• Check directory. If null, replace it with a period .\file.png. That way the backslash will be preserved.
• Also ImagePutFile(0, A_Desktop) doesn't work as expected. It creates a file called "username\desktop.png" instead of creating "username\desktop\2020-09-08 12:12:00.png"
• ImagePutFile(0, A_Desktop "\") works as expected. Checking if the filename is actually a file folder should be considered.

If you want to fix it up, I'll merge the request!