Renaming Tags with namespaces duplicates namespace

[luechtdev]

Version: 0.18.1

When renaming a namespaced XML-Tag - the namespace is duplicated.

Steps to reproduce:

1. Create a namespaced tag like <ns:tagname>
2. Put the cursor on top and press "F2" to rename
3. Change the name (for example ns:tagname2)

Expected Result:
Tag is renamed to <ns:tagname2>

Actual result
Tag is renamed to <ns:ns:tagname2>

[AlexXuChen]

This bug seems deeper than just <ns:..> tags, but actually persists on any tag containing ::
e.g. If you rename <xs:schema> to something, say foo, you will get <xs:foo>.

It also depends on where your cursor is during rename:
e.g. If you rename <ns:tag1> to ns:tag2 and your cursor is hovering ns, the result will be <ns:tag2:tag1>

[rgrunber]

I think the part that is confusing for users is the fact that when you activate rename, the proposed text is ns:foo. Implicitly, this makes someone assume they are renaming the entire tag name (including namespace). If we want to preserve this behaviour of only renaming the left/right component of the :, then we should modify the text that appears in the rename popup.

(| for the cursor position)
In other words : <ns:fo|o> suggests renaming foo & <n|s:foo> suggests renaming ns.

@angelozerr does this make sense ? If so, then I'm guessing we need to change the symbol provider to consider this 2 separate tokens ?