This commit adds support for the `t-for` whose syntax and usage is
similar to the syntax of the for..of loop in JS (and in fact it compiles
to a for..of loop). This looping construct supports looping on arbitrary
iterables and destructuring assignments, which would be difficult to
support in a backward compatible manner on the existing t-foreach
directive.
Before this commit, whenever Owl encounter a t-if, it generates an
anchor (a "hole") in the current block being compiled. However, in some
cases, the content of the t-if may not have any content at all, and the
anchor is then useless. Worse, the code generating the anchor generates
an index based on the number of sub blocks, but if there is no content,
the next anchor being created will have the same index, which then may
cause weird bugs.
A possible way to fix this could be to make sure we increment properly
the anchor index, but we could even do better: not having an anchor at
all.
t-out automatically escaped content when it is a string not marked
with the `markup` function
t-out renders the raw content if it is a Block, or if it has been marked
with the `markup` funtion.
t-esc has been kept since it is safe and is optimized to render text nodes.
all t-raw calls are in fact the same as t-out.
Samuel Degueldre