Preparing bugfix release 0.50.1

[Zoltan Padrah]

Hi,

I'm preparing bug-fix release version 0.50.1, based on release 0.50.0,
with the following changes:
- Fix: The "Open" dialog doesn't show any files when "*|All Files" is
chosen as selector ( https://bugs.kde.org/show_bug.cgi?id=457665 )
- Fix: Segfault when changing element value (
https://github.com/ktechlab/ktechlab/issues/60 )
- Fix: When the schematic project is saved in .circuit format but
w/out .circuit extension it auto-opens as text when the program is
started ( https://bugs.kde.org/show_bug.cgi?id=439016 )
- Fix crash when opening a document using KRecentFilesAction
- Fix 2 possible crashes on some specific routing situations of wires

The code is found in git, in branch "release/0.50".
Please note that this release is not based on git master, it just
back-ports some existing fixes.

In case you have any comments, feedback, then feel free to send them.

Probably next week I will create a release archive + tag + announce the release.

Have fun,

 Zoltan