Allow pkexec xed

[goebbe]

 * Xed version 1.8.2
 * Distribution - (Mint 19)

Issue
gksudo has been removed from Linux Mint 19 - as a result "gksudo xed textfile.txt" does not work any-more.
Suggested workaround: "xed admin:///absolut/path/to/existing/textfile.txt"
The suggested workaround is annoying for several reasons:

1. it requires an absolute path
2. it requires the file to exist already
3. it introduced a new, cumbersome syntax
4. it requires to put the password twice

I suggest to use pkexec instead:
"pkexec xed testfile.txt" <- currently leads to an error message

Expected behaviour
"pkexec xed testfile.txt" should just work like "gksudo xed testfile.txt"

This would allow using relative path, automatic file creation, use of standard syntax.

Other information
Actually the only thing that is missing is a polkit action file that allows xed to be started.
I will upload a policy file that works for me. This file could just be copied into:

/usr/share/polkit-1/actions

com.linuxmint.xed.policy.zip

Thanks, goebbe, for the file - it will be handy for me.

[ia-S-on]

Thank you for this!!