No need to install RPostgreSQL frin source
as.db.data.frame and better handling of TEMP objects

as.db.data.frame for db.data.frame is added. row.names is used as id.col
by default.

Better handling of TEMP objects and table/view names

.db.obj.info is obsolete! Do no use it anymore, but keep it in the
source code. Might be useful later

.db.existsTable/.db.existsTempTable do not work with view. Only
.is.table.or.view works for both table and view.
Made compilable and corrected small bugs/typos
Bug fix

Lots of bugs related to writeTable due to the temporary table problem
Added as.db.data.frame for file

Corrected lots of bugs, most of them are related to how to deal
with row.names, especially when writing file.

Now we use the convention of read.table
Added utility functions:

is.db.data.frame, .unique.string
Added utility function for analyzing formula

* utility function for analyzing formula

* error class

* Short messages after db.data.frame and as.db.data.frame are executed