support partial representation when document contains unrecognized tags

[GoogleCodeExporter]

Please support loading documents with unrecognized tags, either by default or 
as an option that 
can be turned on when constructing a new Yaml instance. This is similar to 
[Issue 31][1].

Steps to Reproduce
1. generate a YAML document containing application specific tags
2. construct a YAML instance with default constructor only
3. attempt to load the document
4. load will fail with an error

Expected Output:
I would prefer that SnakeYAML will load the document as a [partial 
representation][2] per the 
spec, using the node's kind to resolve it as seq, map, or str as appropriate.

Actual Output:

An error:
    The document is not valid YAML:
    could not determine a constructor for the tag '...'
    ...

What version of the product are you using? On what operating system?
SnakeYAML-1.2, OS X 10.6.1 and CenOS Linux


[1] http://code.google.com/p/snakeyaml/issues/detail?id=31
[2] http://yaml.org/spec/1.1/#partial%20representation/

Original issue reported on code.google.com by toolbea...@gmail.com on 8 Dec 2009 at 1:22