templating engine spec

<:import src="some/path">, <:include src="some/path">
    imports the file under some/path into the current file
<:self>, <:this>, <:i>
    these are placeholder elements, that indicate where the template's content should be put (in case you want anything before or after)
<:if condition>
    start if statement
<:else>
    start else statement
<:endif>, <:fi>
    end if/else statement

[:is="foo"]
    the content in the template under the "foo" key will be placed into the element with this attribute
[:of="things"]
    this is a for-loop: all of the items in the "things" array will be used to create elements, with inner content being the i-th item
[:as="currency"]
    use the `currency` helper on the content from the template before insertion
[:void]
    do not fill in the element's inner content

":self", ":this", ":i"
    when written in an attribute, will be replaced with the template content