driver: shorten TAG cfg error message. Fix #73.
driver: use ALARM log for Tag errors.

This change makes `state` and `relay` post a HOST-144 (Comm Tag error)
error to the central ALARM log of the controller upon detecting a problem
with either the configuration or state of a server Tag during
initialisation.

The error is posted with ABORT priority, causing the controller to abort
the program(s). Additional information is printed on the User Menu.
ind_log: split clearing and forcing user menu.

We don't always want to do those at the same time.
driver: add KAREL Vars config to state & relay.

These structures allow runtime configuration of various important settings
and limits. See the wiki for more information on how to access these
structures.

This fixes #2, fixes #8 and fixes #71.

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Backport from driver_ng. The 'KAREL Vars' interface will be replaced
with a proper custom Form and menu in a later commit.
driver: global ABORT on cfg error.

This change makes the controller perform an ABORT in case the
configuration doesn't pass the check.

The FILE-032 error number is re-used for this, in addition to a message
printed to the log window.
relay: update comment to reflect use of config.
relay: change scope to 'routine' for `new_j_pos` variable.

Variable is only used in the `exec_move_()` routine, and does not need to be
accessible to other parts of the program.
driver: avoid accesing program scope variables in routines.

Pass them by reference instead.
driver: bump versions of state and relay.
Move roslaunch to build_depend. Fix #76.