- remove all invertibility checking, will be redundant with LU
- general case: adapt to matrix storage order for better perf
- size 4 case: handle corner cases without falling back to gen case.
- rationalize with selectors instead of compile time if
- add C-style computeInverse()
* update inverse test.
* in snippets, default cout precision to 3 decimal places
* add some cmake module from kdelibs to support btl with cmake 2.4
1) Eigen2 co-installable with Eigen1 without conflict, without affecting programs including either.
2) #include<Eigen/Core> without the .h without conflict with the Core/ directory
3) Uniformize coding style of the CMakeLists.
- make vectors use a separate loop unroller, so that copying a
row-vector into a col-vector is now possible
- add much more documentation
- misc improvements
