Basic PETSCII output column/line counting in putmsg()

When printing a PETSCII Sequence (.seq) file, count the lines/rows and columns similar to how we would if we were using outchar() (but we don't, we use the lower-level outcom() to bypass any translations).

This is related to issue #325:
PETSCII seq files seem to display just fine, the problem I saw was with the auto-pausing (e.g. before a screen-clear) after displaying them.