document that extends tag must be first in template

[Trevor Caira]

The documentation is wrong--the {% extends %} tag must be the very first thing in the template. Otherwise, strange behavior might occur. For example, if C extends B and B extends A, and A provides a block "title", if anything precedes the {% extends %} in B, then C's title block will not override the default in A unless B also provides an {% extends %}.

I've attached a documentation patch to clarify this.

[Malcolm Tredinnick]

I've decided to fix the root problem here, rather than documenting around it. In a moment, I'll commit a change that will allow text prior to the extends tag, so that whitespace won't interfere with things (the text will always be ignored, as per usual "extends" handling, but it allows for more formatting options).

So, thanks for the patch, but we can fix this a different way.

[Malcolm Tredinnick]

(In [7082]) Allow whitespace prior to an "extends" tag. This allows a little more formatting flexibility. Refs #6274.

[Malcolm Tredinnick]

(In [7084]) Fixed #5124 -- Added a reasonable error when "extends" is not the first template tag. Patch from k0001.

Refs #6274.