#7 Entity decoder enhancenment

[Javier Kohen]

Hi, I made a few modifications to the entity decoder so
it's able to decode numerical entities (which Yahoo
uses in their room listings). This is a workaround for
not using a real XML parser from the library.

Additionally I changed the loop to avoid creating a new
substring after each iteration. This should reduce the
object creation in strings that contain a lot Unicode
characters (e.g., all the arabic named rooms).

I ran some tests and the code produces the expected
result for hexadecimal, decimal entities and named
entities (which were already implemented).

[Javier Kohen]