updated travis deps for node-canvas
added profiling helper file
Converted the sources from the Chromium project to Javascript
Fix eslint errors
Optimizations and clean up

TypedArrays are used almost everywhere where it is possible.
FilterInstance has been moved to a single array and accum is now a
typedarray. Having accum as a typed array granted around 30% speed up
alone.
Increment some offsets with ++
Replaced accum by rgba
Replaced ImageOperations by METHODS and removed switch cases

Added more byte_offset incremented with ++ instead of doing math
operations