Support manual terminal columns setting per user

The default terminal columns (still 0/auto) can be overridden with the 'L' command from the user defaults menu. 

Also increased maximum manual terminal rows setting from 99 to 999 - this involved moving the record in user.dat, though the old record value is auto-migrated.
3 jobs for master in 18 minutes and 55 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #1270
build-sbbs

00:15:56

passed #1271
build-sexpots

00:00:32

passed #1272
build-syncterm

00:02:27