Slic3r Prusa Edition 1.42.0-alpha2

Summary:

This a second public alpha release, fixing bugs found in the Slic3r 1.42.0-alpha1 release. Please check the 1.42.0-alpha1 change log for what is new in the 1.42 series.

Fixed upload to a Duet board, which did not start the print when asked for #1502.
Fixed a regression bug in G-code path decimation #1503, #1538.
Fixed a bug in loading / exporting files with spaces and non-latin characters.
Fixed a crash when closing the About dialog #1507.
Slic3r PE 1.41 incorrectly exported system profiles into a config bundle. The system presets contained in such a config bundle are now ignored when importing the config bundle #1511.
Fixed synchronization of scale factor vs. size at the "Object manipulation" panel #1520.
Fixed multiple object rotation, scale factor, and size updates via the "Object manipulation" panel #1521.
A newly added object into the plater is now selected automatically #1525.
Fixed the --datadir parameter #1526.
Fixed export of the plater into STL #1536.
Fixed scaling of multi-part objects through the "Object manipulation" panel #1549.
Fixed "Arrange" function for objects with mirroring applied #1554.
Fixed import of an AMF file, some of the objects may have landed at incorrect positions.
Fixed the "Add instance" function, it did not copy the mirroring information.
Fixed disappearing tabs when switching between SLA/FDM on Linux/GTK #1563, thanks to @smellyfis.

The color picker now opens next to the filament combo box, not in the left top corner of the screen #1496.
Fixed a regression issue, where Slic3r would not open if installed in a directory containing spaces or non-latin characters #1500.
Fixed a crash after switching the user interface language #1501, #1522.
Fixed an annoying behavior, where Slic3r main window would get activated as the mouse entered the 3D view #1512.