add {meta_if} {meta_elsif} {meta_else} {/meta_if} operators to jTpl

[bricet]

I think it would be intersting to have condtionnal possiblities for metas in jTpl.

{if} {elsif} {else} {/if} only concern content for now. So I would like to introduce {meta_if} {meta_elsif} {meta_else} {/meta_if} operators.

Those new operators would add conditions for both content and metas.

I prefer to add new operators instead of mofifying existing for 2 reasons :

1. do not break current behaviour of {if} and Co. 2. when used in a template of a cached zone, metas (and then, with this patch, their conditions) can only use parameters given to the zone. It can NOT use parameters changed or computed by the zone itself. So keeping the ability to disinguish meta and content on one side and content only on the other side seems to me an important possiblity

Here is a patch

[bricet]

I just forgot to say that this patch uses enhancements given by #1198. This could be unplugged removing lines concerning $blockArgsStack if #1200 is OK and #1198 is not.

As for #1199, those conditions will concern {meta} and {meta_html} tags. This should also concern {include} and {zone} if #1196 and #1197 are accepted.

[laurentj]

sorry, too late for 1.2

[laurentj]

I'm almost ok for this patch. I will made little change before to commit it.

[laurentj]

pushed.  https://github.com/jelix/jelix/commit/d80bce6dc79c69d5da9a7470c2c03282062dc67e

thanks for your patch