start to derive a custom mod from installed raws

The goal is to cover cases where a user has edited their own raws.,
turning the edits into a reusable mod.  The trick is in recreating from
an install log to filter out available mods known to be in the install,
and using that as a basis of comparison. - while minimising code
duplication.
Hopefully this works in Py2.7

Moved the get-lines-from-file to a function where it can try different
approaches depending on version.  Only an issue because forcing UTF-8
prevents crashes when trying to merge files of different encodings...
Mod extraction might work

But I haven't tested it, and probably won't until it hooks into the GUI.
The main logic is there though - it just needs a decent way of being
called, finding the installed raws, and entering a name.
Python2-compatible file encoding

I hope, anyway.  The important thing is that lines from files to merge
all have the same encoding, so I'm hoping that this will work.  Not
having Python 2 to check, I'd appreciate feedback!
Clean up, ready for version 0.5

Basically just needs to have a solid way of setting 'global
installed_raws_folder', and hopefully also using
get_installed_mods_from_log() to initialise the tab at start.
Update PyLNP to v0.6 - structure, features, etc
Version 0.5 ready for public use and testing!

While there may be some remaining issues, all the planned features are
now in - so it's ready for widespread use.  Time for modders to check
that their mods work!