Devel merge with Master

Minor problems solved, added new features:

- Solved problem with `rlcompleter`, which didn't work properly when loaded as a
  Lua module.
- Modified `configure.sh` to inform about any error during Lua building.
- Loadable modules are working on MacOs X.
- Added `matrix.svd` and `matrix.diagonalize`.
- Added `stats.pca`, `stats.mean_centered`, `stats.pca_whitening`.