[Petal] condition="true:" superfluous ?

[Jonathan Vanasco]

The Petal docs /cookbook are split evenly in use between
	tal:condition="x"
	tal:condition="true: x"

Most notably, the 'condition' docs use 'true:' while the repeat docs  
do not.

And the true:EXPRESSION Petal docs say:
	"the true: modifiers should always be used when doing Petal  
conditions."

that looked odd, so I looked onto the ZPT website for futher  
clarification

According to the Tal 1.4 specs, which are pretty sparse,  
tal:condition implies a 'true:' already -- making including it  
superfluous.  true is supported in all of the implementations as a  
base modifier, but using it is not necessary in condition

based on that, i'd like to suggest the following changes to the Petal  
docs:

	TAL Syntax
		condition (ifs )
			[ ] remove 'true:' from the abstract and example
			[ ] Append to this line:
					Conditions can be used to display something if an expression is  
true. They can also be used to check that a list exists before  
attempting to loop through it.
				this text:
					TAL assumes conditions are checked to be true-- using the  
modifer 'true:' is not required, but will have no affect if  
included.  To test if something is not true, use the modifier 'not:'  
or 'false'.

	Expressions & Modifiers
		true: EXPRESSION
			[ ] remove this line, as it conflicts with other docs and is wrong
				the true: modifiers should always be used when doing Petal  
conditions

		false: EXPRESSION
			[ ] add this line
				false: is Petal's implementation of a negative boolean check  
using perlish semantics.  The original python TAL specification uses  
not: , which is more pythonic.
				Different TAL engines have decided to implement this modifier in  
different ways-- some use not: , some use false:.   Petal supports both.
				If you need to use your TAL templates with another engine, be  
aware that  you may have to create a custom modifier to support false  
or not.

			[ ] also add after this:
				not: EXPRESSION
				see false: EXPRESSION above