- replace .indexOf("on") with array-style accessor checks
- benchmarking shows ~30% improvement

* 'develop' of github.com:thi-ng/umbrella:
  docs(dgraph-dot): fix typo

 - @thi.ng/hdom-canvas@2.4.12
 - @thi.ng/hdom-mock@1.1.18
 - @thi.ng/hdom@8.0.18
 - @thi.ng/transducers-hdom@2.0.43

- check if opts arg given, but nullish
- fixes PubSub.subscribeTopic(id, xform) version, which would wrongly
  infer `xform` as subscriber instead of transducer
- add tests
- update readme

 - @thi.ng/adjacency@0.1.36
 - @thi.ng/api@6.10.0
 - @thi.ng/arrays@0.6.2
 - @thi.ng/associative@4.0.2
 - @thi.ng/atom@4.1.2
 - @thi.ng/bencode@0.3.17
 - @thi.ng/bitfield@0.3.3
 - @thi.ng/cache@1.0.37
 - @thi.ng/color@1.1.13
 - @thi.ng/compare@1.3.1
 - @thi.ng/compose@1.4.2
 - @thi.ng/csp@1.1.17
 - @thi.ng/dcons@2.2.10
 - @thi.ng/defmulti@1.2.10
 - @thi.ng/dgraph-dot@0.1.2
 - @thi.ng/dgraph@1.2.2
 - @thi.ng/diff@3.2.15
 - @thi.ng/dl-asset@0.3.4
 - @thi.ng/dot@1.2.2
 - @thi.ng/dsp-io-wav@0.1.7
 - @thi.ng/dsp@2.0.9
 - @thi.ng/dynvar@0.1.8
 - @thi.ng/ecs@0.3.9
 - @thi.ng/fsm@2.4.3
 - @thi.ng/geom-accel@2.0.9
 - @thi.ng/geom-api@1.0.9
 - @thi.ng/geom-arc@0.2.20
 - @thi.ng/geom-clip-line@1.0.7
 - @thi.ng/geom-clip-poly@1.0.7
 - @thi.ng/geom-closest-point@0.3.20
 - @thi.ng/geom-hull@0.0.40
 - @thi.ng/geom-isec@0.4.9
 - @thi.ng/geom-isoline@0.1.38
 - @thi.ng/geom-poly-utils@0.1.38
 - @thi.ng/geom-resample@0.2.20
 - @thi.ng/geom-splines@0.5.7
 - @thi.ng/geom-subdiv-curve@0.1.37
 - @thi.ng/geom-tessellate@0.2.20
 - @thi.ng/geom-voronoi@0.1.38
 - @thi.ng/geom@1.8.8
 - @thi.ng/gp@0.1.10
 - @thi.ng/grid-iterators@0.3.7
 - @thi.ng/hdom-canvas@2.4.13
 - @thi.ng/hdom-components@3.2.3
 - @thi.ng/hdom-mock@1.1.19
 - @thi.ng/hdom@8.0.19
 - @thi.ng/heaps@1.2.9
 - @thi.ng/hiccup-carbon-icons@1.0.32
 - @thi.ng/hiccup-css@1.1.17
 - @thi.ng/hiccup-markdown@1.2.3
 - @thi.ng/hiccup-svg@3.4.10
 - @thi.ng/hiccup@3.2.17
 - @thi.ng/idgen@0.2.8
 - @thi.ng/iges@1.1.22
 - @thi.ng/imgui@0.2.8
 - @thi.ng/interceptors@2.2.13
 - @thi.ng/intervals@2.0.9
 - @thi.ng/iterators@5.1.17
 - @thi.ng/layout@0.1.6
 - @thi.ng/leb128@1.0.11
 - @thi.ng/lsys@0.2.35
 - @thi.ng/malloc@4.1.10
 - @thi.ng/matrices@0.6.7
 - @thi.ng/memoize@2.0.6
 - @thi.ng/mime@0.1.6
 - @thi.ng/morton@2.0.8
 - @thi.ng/pixel@0.1.15
 - @thi.ng/pointfree-lang@1.2.2
 - @thi.ng/pointfree@1.3.2
 - @thi.ng/poisson@1.0.9
 - @thi.ng/porter-duff@0.1.14
 - @thi.ng/ramp@0.1.9
 - @thi.ng/random@1.4.4
 - @thi.ng/range-coder@1.0.37
 - @thi.ng/resolve-map@4.1.18
 - @thi.ng/router@2.0.16
 - @thi.ng/rstream-csp@2.0.11
 - @thi.ng/rstream-dot@1.1.18
 - @thi.ng/rstream-gestures@2.0.10
 - @thi.ng/rstream-graph@3.2.11
 - @thi.ng/rstream-log-file@0.1.33
 - @thi.ng/rstream-log@3.1.18
 - @thi.ng/rstream-query@1.1.18
 - @thi.ng/rstream@4.0.3
 - @thi.ng/sax@1.1.17
 - @thi.ng/scenegraph@0.1.10
 - @thi.ng/seq@0.2.8
 - @thi.ng/sexpr@0.2.11
 - @thi.ng/shader-ast-glsl@0.1.20
 - @thi.ng/shader-ast-js@0.4.13
 - @thi.ng/shader-ast-stdlib@0.3.13
 - @thi.ng/shader-ast@0.3.14
 - @thi.ng/simd@0.1.11
 - @thi.ng/soa@0.1.11
 - @thi.ng/sparse@0.1.33
 - @thi.ng/strings@1.8.2
 - @thi.ng/system@0.2.2
 - @thi.ng/text-canvas@0.2.4
 - @thi.ng/transducers-binary@0.5.7
 - @thi.ng/transducers-fsm@1.1.17
 - @thi.ng/transducers-hdom@2.0.44
 - @thi.ng/transducers-patch@0.1.7
 - @thi.ng/transducers-stats@1.1.17
 - @thi.ng/transducers@6.4.4
 - @thi.ng/vector-pools@1.0.20
 - @thi.ng/vectors@4.2.4
 - @thi.ng/webgl-msdf@0.1.21
 - @thi.ng/webgl-shadertoy@0.2.8
 - @thi.ng/webgl@1.0.3
 - @thi.ng/zipper@0.1.10