ALPM API adjustments for sanity and consistency

ALPM API adjustments for sanity and consistency

This makes several small adjustments to our exposed method names, and in
one case, parameters. The justification here is to make methods less odd
in their naming convention. If a method takes an alpm_db_t argument, the
method should be named 'alpm_db_*', but perhaps more importantly, if it
doesn't take a database as the first parameter, it should not.

Summary of changes:

    alpm_db_register_sync   -> alpm_register_syncdb
    alpm_db_unregister_all  -> alpm_unregister_all_syncdbs
    alpm_option_get_localdb -> aplpm_get_localdb
    alpm_option_get_syncdbs -> aplpm_get_syncdbs
    alpm_db_readgroup       -> alpm_db_get_group
    alpm_db_set_pkgreason   -> alpm_pkg_set_reason

All methods keep the same argument list except for alpm_pkg_set_reason;
there we drop the 'handle' argument as it can be retrieved from the
passed in package object.

Signed-off-by: Dan McGee <dan@archlinux.org>