Update some GPU tests

first commit to Make equal_computations more efficient

Update printing and plotting sections in tutorials

Fix scan test for float64

Fix crash in Alloc grad

Fp16 merge

Lstm fixes

Downsample: C implementation for average, sum

Fix spelling in documentation

[TEST] fix buildbot Gpu test

(#2613, #2747) Add handling of negative axis for Join and GpuJoin

Maxpool c code

Better doc of function_dump