Refactor

[mschauer]

the src/ folder should only contain files which are included in the module.

[mschauer]

So I moved around things, fixed warnings, some things:

• It is better to use joinpath(path, file) than path*"/"*file
• JLD does not work very well anymore, JDL2 is the better choice.
• I introduced a onemask working like zero(A) just setting everything to 1
• Backsolve now calls the lufact with pivoting, for now I use the lu factorisation explicitly in https://github.com/mschauer/BridgeLandmarks.jl/blob/master/src/lmguid.jl#L232
• Updated the project
• Some smaller things