...instead of running apk every time to get the list of installed
packages and their versions. The internal package database from
apk has the same format, as the extracted APKINDEX file (except
that it has more key-value pairs, which we ignore/do not need
right now). So the APKINDEX code has been extended to parse both
tar-packed APKINDEX files and regular text files in the APKINDEX
format.
This is required for #108, for a better detection of outdated
packages (because the internal package database saves the
package's timestamp, too). A nice benefit is, that this is faster
than calling apk every time and it doesn't fill up the log as much.
I've also used this improved function for determining the apk
version (for the outdated version check), and I've deleted
pmb.parse.other.package_split(), as it is not needed anymore.
* pmb/challenge/apk.py had to be renamed to pmb/challenge/apk_file.py,
so the "internal" functions of that file could be accessed, while
still providing the short notation pmb.challenge.apk().
* zap asks for each buildroot_* chroot, if you want to remove it, not
only for the one with the device arch
* add new pmb.chroot.tempfolder() function, that creates a temporary
folder, that belongs to "user" and deletes it, if it already exists.
this function gets used in a few challenge testcases.
