[Veltools] ParameterParser patch

[Nathan Bubna <na...@esha.com>]

Nathan said:
> I've also been working on my search result paging tool.  I should have
> something to contribute there shortly.  I also intend to get into the
whole
> ParameterParser mess again soon.  :-)

...and so i did.  i went through it and:

-de-staticized (is that a word?) the parsing methods
-implemented ViewTool so it can be conveniently used as a view tool
-added an alternate constructor for convenience in non-template situations
-changed getNumber (and thereby it's dependents) to catch NFE's and return
null instead

i think these changes should make this class immensely easier to use at a
miniscule cost to performance.  yes, it is no longer safe to use as an
application or session scoped tool, but IMO it is intrinsically
request-scope (it exists only to parse request parameters!) and should be
used as such.

the patch for these changes is attached.

thanks!

Nathan Bubna
nathan@esha.com