[Ohrrpgce] SVN: teeemcee/8370 Remove xstring/xstringright, replacing them with RelPos values

[subversion at HamsterRepublic.com]

teeemcee
2017-01-29 01:35:03 -0800 (Sun, 29 Jan 2017)
367
Remove xstring/xstringright, replacing them with RelPos values

In most cases I used pCentered instead of pCenteredLeft (which forces
the start of the string to be shown) because it rarely seemed necessary.
When everything gets converted to slices it's a pain to support that behaviour
anyway; better to wrap text.
There are a couple places where I did use wrapprint.
---
U   wip/bmod.rbas
U   wip/common.bi
U   wip/common.rbas
U   wip/customsubs.rbas
U   wip/game.bas
U   wip/mapsubs.bas
U   wip/menustuf.rbas
U   wip/moresubs.rbas
U   wip/scripting.bas
U   wip/yetmore2.bas