add a commandline flag for dynamically specifying reverse-search editor command

[Andreas Naumann]

Hey all okular developers,

please let me first introduce my self, since i am new to the list.

My name is Andreas and I am from Germany. I do have several years
experience in (scientific) Softwaredevelopment with C++. Since I use the
KDE desktop quite regularly, I thought, I could also give something back
to the community.

So, I was looking for some task, I am interested in and which also
serves as a starting point to learn the code base.

Thus I selected the bug263732 <https://bugs.kde.org/show_bug.cgi?id=263732>

During studying the code and trying to fix it, I asked myself some
question on the code and workflow:

1. The commandline is parsed by the commandline parser from Qt. But the
arguments are passed around using a string. Everytime a function needs
to check for an argument, it deserializes the string to retrieve the value.

That workflow has the advantage, that it requires only a QString to pass
the data to other functions.
I prefer to have a data structure, which contains the arguments as fields.

Is there any other disadvantage in using a struct instead of a string?

2. Several tests fail. Is that intended, or forgotten? I did not yet dig
deeper into the codebase to understand, what the tests do.


Greetings,
Andreas