Add separator to custom footer text item

[JasonInOttawa]

This change is 

[hius07]

I'm not sure about this.
Patterns are for variables, like opened book metadata, reading progress or device/system state.
Fixed symbols can be written into the string directly.

[JasonInOttawa]

I did do that with a cut and paste, but it was hard to find the right symbol and paste it on a Kobo. I did it in a desktop application and then manually updated the settings file on the Kobo. Thought it would be easier this way.

[JasonInOttawa]

Also I believe (but haven't tried) that changing the separator in settings will update this automatically

[Frenzie]

Also I believe (but haven't tried) that changing the separator in settings will update this automatically

Correct. It is indeed a type of variable in that sense.

[hius07]

I still don't feel the settings to be variables. Anyway, up to @Frenzie.

If approved, this pattern should be under is_doc_required, otherwise it'll crash in the file browser.

UPD: not under is_doc_required but safeguarded:
if patterns["%r"] and self.document then

[hius07]

Depending on the settings it can be not an icon, so just separator.

[hius07]

UPD: no need of this local at all.

[JasonInOttawa]

Local removed

[hius07]

genSeparator always returns something, the check is not needed.

[JasonInOttawa]

Check removed

[Frenzie]

I still don't feel the settings to be variables. Anyway, up to @Frenzie.

I think it makes sense to have your added separators automatically change along with any built-in ones.

[JasonInOttawa]

I set my separator to all the choices (vertical bar/bullet/dot/no separator) and noticed that the separator changed each time and did not crash when "no separator" was chosen