ViewHelper to force compiling to a static string

Used around chunks of template code where you want the output of said template code to be compiled to a static string (rather than a collection of compiled nodes, as is the usual behavior).

The effect is that none of the child ViewHelpers or nodes used inside this tag will be evaluated when rendering the template once it is compiled. It will essentially replace all logic inside the tag with a plain string output.

Works by turning the compile method into a method that renders the child nodes and returns the resulting content directly as a string variable.

You can use this with great effect to further optimise the performance of your templates: in use cases where chunks of template code depend on static variables (like thoese in {settings} for example) and those variables never change, and the template uses no other dynamic variables, forcing the template to compile that chunk to a static string can save a lot of operations when rendering the compiled template.

NB: NOT TO BE USED FOR CACHING ANYTHING OTHER THAN STRING- COMPATIBLE OUTPUT!

USE WITH CARE! WILL PRESERVE EVERYTHING RENDERED, INCLUDING POTENTIALLY SENSITIVE DATA CONTAINED IN OUTPUT!

= Examples =

<f:if condition="{var}">Is always evaluated also when compiled</f:if> <f:cache.static>

<f:if condition="{othervar}">
    Will only be evaluated once and this output will be
    cached as a static string with no logic attached.
    The compiled template will not contain neither the
    condition ViewHelperNodes or the variable accessor
    that are used inside this node.
</f:if>

</f:cache.static> This is also evaluated when compiled (static node is closed) <f:if condition="{var}">Also evaluated; is outside static node</f:if>