[Ohrrpgce] SVN: teeemcee/11158 showstringat now supports newlines. Add some relpos testcases & docs.

[subversion at HamsterRepublic.com]

teeemcee
2019-05-11 22:19:45 -0700 (Sat, 11 May 2019)
182
showstringat now supports newlines. Add some relpos testcases & docs.

Also update centerstringat default args to center the string on the screen
regardless of the screen resolution.
---
U   wip/allmodex.bas
U   wip/docs/plotdict.xml
U   wip/plotscr.hsd
U   wip/util.bas
U   wip/util.bi
U   wip/whatsnew.txt
U   wip/yetmore2.bas