If we want to generate dynamically svg components, it is useful to be
able to define components with a <g> tag as root, and then getting the
correct namespace.
closes#302
Snabbdom supports svg, but it adds the namespace at the creation of the
virtual node. However, owl works slightly differently: it adds children
after creating the parent virtual node.
So, we need to actually call the addNS method after the children nodes
have been created.
As a bonus, this is slightly faster than snabbdom: we only check at
template compilation time once if a node is a svg.
Before this commit, QWeb crashed when it had to deal with a t-call with
multiple sub nodes on the same line, and one text node:
<t t-call="SomeTemplate">
<span>hey</span> <span>hey</span>
</t>
This was because we need to compile the content to be able to extract
all possible t-set t-value statements. But doing so means that we had a
multiple root templates, which caused a crash in this case.
Solving this issue is simple: the sub template is compiled with the flag
allowMultipleRoots set to true.
This is a difficult part of owl: we need to be able to reconcile the
vdom generated (this is done with our virtual dom algorithm), but also
to be able to reconcile the proper components.
The issue here is that when we are in a list, with a t-key attribute on all
list nodes, and those list nodes contains sub component, then the
component system used the index of the list, and did not take into
account the key from the parent. The fix is to keep track of the
current key in the context, and uses that as a part of the templateId.
Géry Debongnie