Backport various improvements from Tcl 8.5
merge-mark
Add some extra paths on Windows for fincing tclConfig.sh, for mSys and Cygwin shell.
Improve some comments and quoting, no change in functionality
Improve some comments and quoting, no change in functionality. 
Only check for refCount == 0x61616161 for TCL_MEM_DEBUG build.
Suggested fix for bug 3604576: msgcat -1.5.0.tm error on windows XP, inclusive bump to version 1.5.1.
Changelog entry still missing.
Finer granulated catch
[Bug 3604576]: msgcat-1.5.0.tm error on windows XP
[Bug 3604576]: msgcat-1.5.0.tm error on windows XP
ChangeLog corrected: msgcat issue must not be XP specific
ChangeLog corrected: msgcat issue must not be XP specific
merge-mark
New branch bug-3604074 with improved patch to correct fixempties() failure
to converge.
Eliminate last use of Tcl_SetResult (except the use in the Test suite)
Fix depreciation message in tcl.h
3604074 Fix regexp optimization to stop hanging on the expression
((((((((a)*)*)*)*)*)*)*)* .  Thanks to Bjørn Grathwohl for discovery.
revise test numbering for forward merging
3604074 Fix regexp optimization to stop hanging on the expression
((((((((a)*)*)*)*)*)*)*)* .  Thanks to Bjørn Grathwohl for discovery.
3604074 Fix regexp optimization to stop hanging on the expression
((((((((a)*)*)*)*)*)*)*)* .  Thanks to Bjørn Grathwohl for discovery.
merge trunk