CLI args: reorganize parsing

CLI args: reorganize parsing

Split parsing of CLI arguments into separate functions:

parsearg_op (operations)
parsearg_global (global options)
parsearg_{database,query,remove,sync,deptest,upgrade}

Organization strictly follows the manpage (even where the manpage is
incorrect) - these cases will be fixed in the following commits.

Switch cases are copy/pasted and statements unrelated to chosen
operation are deleted.

Parsing logic adjusted as follows:

1) Parse operation
2) If we can bail out early (duplicate op, help/version requested) do so
3) Parse arguments again:
    foreach arg:
        if arg is operation:
            continue
        tryparse_args_specific_to_op
        if unsuccessful tryparse_args_global
        if unsuccessful print error message and exit

Signed-off-by: Xavier Chantry <chantry.xavier@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>