Simplify handling and non-splitted tests and include split_test_helper.h instead of re-generating it. This also allows us to modify it without breaking existing build folder.

(files from previous build were kept on the server, with outdated/garbled
information)

The documentation update script now wipes build/doc/html
before rebuilding stuff. Most of the time/cpu consuming is spent in
compiling snippets, so we don't loose that much.

Added file extensions to our unit test scripts to prevent MSVC from failing to build because of name clashes.

Notice that CTest 2.8 supports the -j argument, although that is undocumented.
Last commit of 2009! Happy new year to all!

  Instead, they honor the EIGEN_JOBS environment variable if defined.
* The syntax ${BLABLA} in bash scripts was conflicting with CMake configured
  file syntax. Resolved by using the @ONLY option and the @BLABLA@ syntax.

Otherwise, buildtests will be run with a second argument of "" if check
is called with only one argument, which leads to infinitely many jobs.

* tests now honor EIGEN_REPEAT and EIGEN_SEED if no arguments were passed

* support unsupported/
* use egrep instead of grep, properly escape special chars.

* bump version to 2.91.0
* add FindEigen3.cmake

* DiagonalMatrix:
   - add MaxSizeAtCompileTime parameter
   - DiagonalOnTheLeft ---> OnTheLeft
   - fix bug in DiagonalMatrix::setIdentity()

  (useful for porting)
* maketests really has to be in test/

* update the messages
* rename EIGEN_CMAKE_RUN_FROM_CTEST to something saner