Added support for custom scalars
Removed unnecessary parentheses
Make FullPivHouseholderQR::solve returns the least-square solution instead of aborting if no exact solution exist
Merged in advanpix/eigen-mp-devs (pull request #31)

Added support for custom scalars in SparseLU
Make the static assertions on maximal fixed size object use EIGEN_STACK_ALLOCATION_LIMIT, and raise its default value to 128KB
Fix compilation with non-msvc compilers.
Fix indentation
BDCSVD: Compute SVD of combined problem directly.
First step at implementing final stage in BDCSVD algorithm.
Uses bisection method to solve nonlinear equation.
Still lots of room for optimization.

--HG--
extra : transplant_source : %7F%89%E0%A5%9Ft%04%2B%B0%CA0%2BE%E9%8AHva%A6F