This is implemented as a new SetKeyboardLayout job that does the work.
Portions of the code are adapted from systemd-localed's source code,
which is under a compatible license (LGPLv2.1+, can be converted to our
GPLv3+ license). I ported it from C to to C++/Qt and made some minor
tweaks to the mapping logic (from X11 to vconsole layouts) though.
Fixes#31.
Tested on a Fedora Remix (Kannolo 21) with the default module settings
(finds the converted X11 keymaps for the virtual console) and with
convertedKeymapPath: "" (does the legacy keymap conversion as expected).
This also adds ImageRegistry, a SVG cache, a bunch of utility functions
for shared pixmaps in CalamaresUtilsGui and renames several qrc files
in viewmodules.
Module descriptors are now module.desc, no configuration allowed inside.
Module config files are <modulename>.conf, installed in
share/calamares/modules.
settings.conf is read from /etc/calamares, then share/calamares, and if
running with --debug also in the current dir.
Module config files are read from /etc/calamares/modules, then
share/calamares/modules, and if running with --debug also in
src/modules/<modulename> relative to the current dir.
