GUI: Blocks should be limited in length

[John-Holt-Tessella]

If the block name is too long it does not get passed correctly to addToSet. It gets truncated in the run control settings file:

[2018-10-09 15:30:08] dbLoadRecords("C:/Instrument/Apps/EPICS/support/RunControl/master/db/runcontrol.db","P=TE:NDW1032:,PV=TE:NDW1032:CS:SB:rcptt_d5436e501bad4797b281a0ee")

[2018-10-09 15:30:08] Can't set "TE:NDW1032:CS:SB:rcptt_d5436e501bad4797b281a0ee:RC:_SEQ.STR2" to "TE:NDW1032:CS:SB:rcptt_d5436e501bad4797b281a0ee"

If it is much too long then you get:

[2018-10-09 16:50:54] Can't create record "TE:NDW1798:CS:SB:a23456789012345678901234567890123456789012345678901234567890123456789012345678901245678901234568789012345678901234567801234567865604:RC:HIGH" of type "ao"

1. Find out what the limit is for this and place a restriction in the gui configuration.
2. Write a test which checks that the run control works for long pv names.
3. Check all current configurations for blocknames that are too long.

Work out what addToSet (EPICS\support\asubFunctions\master\asubFunctionsApp\src\setFunctions.c) does and add documetnations to function and to records (record(aSub, "$(PV):RC:_OUT:DO"), record(sseq, "$(PV):RC:_SEQ") that calls it (in EPICS\support\RunControl\master\db\runcontrol.db).

See #2773 for limit in archiver

[John-Holt-Tessella]

Add to config checker

[John-Holt-Tessella]

+1 Seen on LOQ in the wild

[John-Holt-Tessella]

Block limit is currently 20.

18 character for prefix + CS:SB: total length into the PV is 40 characters so 20 is a nice number.

This can be lengthened when EPICS 7 is done #4416

Make sure this does not invalidate too many blocks before adding it by using config checker.

Many instruments violate this so we should NOT enforce it. We should instead fix run control with epics 7.
Then 60 characters for a pv name so PV + block prefix and instrument and :AC:_CALCSCAN postfix: 60 - 18 - 13 = 29.

This is below the next limit seen in #2773 is the next known limit which is 100 - 18 ~ 80 characters in a block name. (Archiver database channel name size). Close this ticket when done.

[kjwoodsISIS]

Consider enforcing a limit of 80 in the GUI, so that no-one can violate the EPICS 7 limit.