Detect api.xml format doc files

[Redth]

Originally when JavaDocletType._ApiXml was added, I forgot to put some logic in the method which determines what kind of doclet type to use from the file path itself, which this addresses.

[jonpryor]

Why allocate a new char[]? That seems like a waste of memory.

[jonpryor]

We use Mono's coding convention, so please use a space before ( here and elsewhere.

[jonpryor]

You shouldn't ignore the return value. You should keep it, for the subsequent new string() invocation.

This allows you to reuse the existing buf instance w/o creating a new one.

[jonpryor]

Basically:

string rawXml = null;
using (var reader = File.OpenText (path)) {
    int len = reader.ReadBlock (but, 0, buf.Length);
    rawXml = new string (but, 0, len);
}