Since saturnin's dedication to be "meta-command" builder, the distinction
between "meta" and something else does not make much sense.

E.g.: ` bz 1234` should now work the same as `bz 1234`.

 *  dmenu really needs to have the arguments split,
 *  and uris use cat to enable support for - as STDIN

Workspace-based choice was not really that useful, so removing to get
rid of jq dependency

Old code had problems with trailing space--which did not manifest itself
until now when I tried to use infix query (e.g. 'foo%sbar' would always
result in space after '%s').

Turns out that `read` with multiple variables splits the line just as we
need it with no extra leading/trailing junk.

If user does not provide mandatory parameter, `shift 2` will fail but
will not shift anything, resulting in infinite loop.

The routines are all basically related to the meta-command functions.

Make them shorter but also sortable (ie. 'conv' for converters, 'flt'
for filters.)