Fixed compilation on VC12, thanks to Chen Li for the fix.
Force the gaussian type in BoxMuller case (without spez the outer class) .

Example uses the spez now; making life harder to compilers (and detecting problems earlier).
Tested ok on VC9 & gcc
Implicit types for VC12 compilation, thanks to Cheng Li and Luigi.
Fixed clang compilation. Thanks to Klaus for the tip.
Merge pull request #147.