Merge pull request #53 from fluffynuts/master

* change Firebird left/right field delimiters to double-quotes
Merge pull request #54 from fluffynuts/master

* fix failing test that I missed in the last round ):
* add ability to run FirebirdEmbedded tests
* add FirebirdEmbedded test against in-field bug: count query does not
  quote source fields
* update other Count tests to expect appropriate table quoting
* introduce FunctionQueryField base class for function extension in the
  future. FunctionQueryField implements ISelfFormattingField to produce
  valid sql parts representing the function at hand. Currently only
  supports the functionality required to support CountQueryField but
  can be extended later for other functions and parameters,
  including constant values and nested function calls
* introduce CountFunctionQueryField to create valid count parts for
  sql statements
* use CountFunctionQueryField where a count is required