Patch to version 0.79

[Jack Poulson]

Dear all,

Due to several routines being added and a bug being found, I've released version 0.79-p1:
http://elemental.googlecode.com/files/elemental-0.79-p1.tgz

In particular, the main changes were:

Features
========
- Added thresholded version of BusingerGolub QR
- Added interpolative decompositions (ID's)
- Added skeleton decompositions
- Added configurable tolerance for pseudoinverses

Bug fixes
=========
- Fixed several recently introduced mistakes in Determinant calculations

Maintenance
===========
- Fixed several mistakes in the documentation
- Merged HermitianPseudoinverse.hpp into Pseudoinverse.hpp

I'm excited to finally have interpolative and skeleton decompositions in Elemental. Randomized implementations will almost certainly be faster in many circumstances, but I think that it is good to start with the deterministic implementations. I would also like to add in a routine for randomized power-method-based two-norm estimation which returns an estimate within a specified factor of the truth with a specified maximum probability of failure.

Many thanks to Mark Tygert for clarifying many of the design decisions in his id_dist package:
http://cims.nyu.edu/~tygert/software.html

as well as clearing up the history and conventions behind the various names for (pseudo-)skeleton/CUR decompositions.

Jack