Misc: Beautified codes

1.  Removing 'onload="main()"' from <body>
2.  Backcalling: 'let @ -> gl' -> '<- (.call gl)'
Added missing codes

'vertexPositionAttribute'
Added math libraries

sylvester, glUtils
Made it render a plain white square
Minified glUtils.js
Added `uglifyjs` to the Makefile script