fixes #666

.. and back to read-only after finishing with modifications.

fixes #512

if package arch is not set, do not append anything to repository.
if arch is set, it is appended to repository.

Unsigned indexes should not be needed anymore anyway.

Instead of having a null pointer, use a dummy array which just
says the array is empty. This helps in multiple places of the code
which would otherwise need explicitly need to check first if the
array exists. This has been cause of multiple seg.faults in the
past as the array check is easily omitted.

This also removes (or fixes) all existing checks accordingly.

wget:ing local files results in error and is useless.

this helps boots sequence when network is not available.

so user can override trusted keys directory and repositories file.

previously they might have been skipped on certain situations.
this also fixes some other reverse dependency enforcements and
implements new "pending" state for locked name.

this way we never change cwd, and relative filenames are always
parsed consistently. this also helps filename construction in many
places. this patch also changes '--root' to override location of
all configuration to be in the new root. previously it depended
on the file which one was used.

- error codes for verification failure types
- fix some fdb corruption on file migration
- combine some dependency parsing code
- fix versioned dependencies

prefer index in the new format as signed .tar.gz.

this also convers scripts file to a tar archive.

snprintf is dog slow. make the blob stuff have some helper functions
so we can use them in code paths that are executed often.

This will update the repository cache upon db_open.

check for the full filename to match an expected pattern or
delete it (so we delete files with .new, .new.backup, etc.).
final part of remote package caching: fixes #49.

that way we get the same result as the 'apk add world' at boot
time; it might differ from currently installed set (ref #49).

more fine grained control what to load, and rename some of the
flags to be shorter.

Administrative tool to download or delete files to/from the cache.