Add basic usage example to readme
Implement dbFetch
Proof-read news
Use R data types
Remove USING_R macro
Eliminate R version based defines
Eliminate more S+ shims
Remove "Green book" macros
Removing even more S4 macros
Eliminate use of RInternals.

Use SEXP instead of s_object*, and eliminate some pointless typedefs.
More conversion of S-api to R-api
Merge RS-DBI.h into RS-MySQL.h
Since driver is singleton, use constant for id.
Split RS-DBI into individual files
Split RS-MySQL.c into individual files