ALPM: ALPM_QUESTION_LOCAL_NEWER was removed

Also following constants were "re-indexed" so a recompile was due to reflect
those API changes.
ALPM: Event OPTDEP_REQUIRED renamed to OPTDEP_REMOVAL
Free memory from ALPM when needed

New API now allows/requires us to free memory of data we were given.
Update to ALPM's new event system
Revert handling log messages as event

Reverts changes from "Update to ALPM's new event system" (c00ecc9d) that made
log messages an event back into a separate callback.
Support ALPM's new event RETRIEVE_{DONE,FAILED}
Support ALPM's new events for pac* files
Support ALPM's new events PKGDOWNLOAD_*

This allows to know when the download of a package file begins, and when
it ends (whether successully or not).

So we can move some code out of every progress update, to the start of
a download, or the end of it.

This will also fix a bug where if a download failed, its progress bar
would never go away (since it was based on reaching 100%). Now not only
does it go away, but the size will show up in red afterwards, to
indicate there was a failure.
Update to ALPM's new question system
updater: Add $PACFILES to cmdlines
Default siglevel from pacman.conf wasn't set

It was loaded from the file, but not se in ALPM (during checks/simulation)
kalu-dbus: Minor tweaks
kalu-dbus: Add downloadonly argument to Init()

When TRUE, the transaction will be set to only download packages. One
still needs to call GetPackages() & SysUpgrade() as usual.
simulation: Add button to download packages only
polkit: Add org.jjk.kalu.sysupgrade.downloadonly
gen-interface: Fix bug on return value ("out" arguments)
Minor tweaks

Silencing warnings.
kalu-updater: Fix handling MethodFailed w/out callback

The flag is_running wasn't then reset.
kalu-updater: Fix memory leaks
updater: Add ability to abort a transaction

kalu-dbus now handles SIGINT to abort the current ALPM transaction. Said
transaction (i.e. the sysupgrade, or download-only) will now be performed
in a new thread, so that kalu-dbus can still process other method calls
at the same time, specifically the new method Abort.

Abort() will send SIGINT into the sysupgrade thread, so that the signal
may be caught be ALPM (in case of a download, to properly abort it) before
it is raised again, and then we'll interrupt the transaction.

In effect, this is like pressing ^C from your pacman-running terminal.