Item9050: Debugging support: add TRACE mode for templates

Priority:	CurrentState:	AppliesTo:	Component:	WaitingFor:
Normal	Closed	Engine		Main.CrawfordCurrie

Years ago I evaluated use constant and was able to measure a performance impact of using it. I just tried it again with the latest perl, and it seems a lot quicker now, so I'm going to reinstate it in place of all those nasty sub TRACE { 0 } obscurities, as it improves readibility.

Also, there's an identifiable need for a TRACE mode for the Foswiki::Template module that annotates the output to show what templates were expanded to generate the output.

-- CrawfordCurrie - 22 May 2010

Re-opened to fix RcsTests

-- PaulHarvey - 23 May 2010

Cleaned up further and extended SD's line eating around comments to whitespace eating, which seems to cure quite a few things.

-- CrawfordCurrie - 25 May 2010

Re-opened for some more changes.

-- CrawfordCurrie - 16 Sep 2010