New features and optimizations for animint

by Tony Tsai for R Project for Statistical Computing

The project aims to implement several new features and optimize the compilation for animint. The new features includes new aesthetics that only make sense on the web/SVG, new aesthectics for configuring the appearance of selected items, shape and arrow aesthetics. .parallel and .compress options, and a new approach of generating chunck TSV files will be added to animint compiler for optimizations.