Merge branch 'develop' (early part)
Merge branch 'master' into develop
improve broadcast-compatible function
minor editing
fix default zero-matrix? test
extra tests
improve sequence conversion to vectors
improve default convert-to-nested-vectors
improve convert-to-nested-vectors default impl
fixes for as-vector and wrappers
improve element-seq for persistent vectors
fix NDArray matrix-add and matrix-sub
extra NDArray mutable add and sub regression test
fix nil transpose, minor edits
nil tests and fixes
tests for scalar numbers
number tests and fixes
tests and fixes for nil scalar value
more nil tests and fixes
tidy