Replace AbstractFloat with Real, working on #13

[tlnagy]

Went through and replaced the AbstractFloat type with Real. Still need to implement new tests.

[KristofferC]

Thanks for looking into this. I believe @testloop got merged into @testset at https://github.com/IainNZ/BaseTestNext.jl so we should update those.

[tlnagy]

Yup. I saw that too. I'll open a new PR for that and then rebase this.

[tlnagy]

Where would you recommend putting test cases for integers? In test/test_monkey.jl?

[KristofferC]

For deterministic tests maybe either in the ``knnorinrange` test file. The monkey file is mostly for "random" test.

[tlnagy]

Okay. I'm getting the following error when using my example from #13:

data = rand(1:4, (10, 10^4))
balltree = BallTree(data, Hamming())

LoadError: InexactError()
while loading In[6], in expression starting on line 2

 in generic_scale! at linalg/generic.jl:12
 in create_bsphere at /Users/tamasnagy/.julia/v0.4/NearestNeighbors/src/hyperspheres.jl:33
 in build_BallTree at /Users/tamasnagy/.julia/v0.4/NearestNeighbors/src/ball_tree.jl:98
 in build_BallTree at /Users/tamasnagy/.julia/v0.4/NearestNeighbors/src/ball_tree.jl:113 (repeats 10 times)
 in BallTree at /Users/tamasnagy/.julia/v0.4/NearestNeighbors/src/ball_tree.jl:67

Which I tracked down to here: JuliaLang/julia#12912. I'm using 0.4.1 which doesn't have this patch (JuliaLang/julia@ab0db5c) yet.

[KristofferC]

I guess the hyper spheres are created with Int parameter so that the center and radius are of integer type. These will of course not in general be integral even if the input data is integers.

For input data of integer the type of the hyper spheres should probably just be float64s.