Added manual files, and make the package compilable
Added port in db.connect

Also let distributed.by == "" be the signature for randomly distributed
table in db.writeTable
Minor changes to improve usability
Tested the current db connection functions

* Removed unnecessary argument checks in the internal functions, and
  only keep argument checks for functions that are exposed to the users

* Various minor changes to improve the usability

* Added fetch function

* Corrected various small bugs

* Added .db.str2vec function
Better return values for db.connect and db.disconnect

* db.connect returns connection ID

* db.disconnect returns TRUE/FALSE
Start implementing db.data.frame
Moved .db.str2vec into utilities-generic.R
Added db.data.frame methods

Improved the doc for methods

Also added classes and export them
Added manual for classes

Also improved the name of the classes
Added dim and names methods for db.data.frame

The package is fully compilable now