Fastcluster

• Changed the name of the external function from the outdated "Rcpp_linkage"
to "fastcluster".

• Registered the external function "fastcluster" in R.

• Configured the C header inclusions to work on Fedora (thanks to Peter
Langfelder).

• File README: Removed the warning about false results from the flashClust
package since the new flashClust version 1.01 has this error corrected.

• Cleaned the test file fastcluster_test.R up. (No dependence on the MASS
package any more)

• File DESCRIPTION: Fixed a typo

• Removed the dependence on Rcpp; only R's original C interface is used.

• Initial release, dependent on Rcpp. Not available on CRAN.