Bumped version number to 0.25.0-SNAPSHOT
Math.js now immediately returns a default instance of mathjs, no need to create an instance every time you want to use the library.
Added more configuration examples
Fixed a typo in the getting started
Fixed sourceMappingURL being added twice to math.min.js
Refactored `ConstantNode` to make it more flexible to various types of input
Added some comments
Fixed a comment giving issues with template engines (because it contained `{{`)
Changed hard links to documentation pages from github to the website
Fixed a link
Created docs page with alphabetical function reference
Added categorical function reference
Removed categorical function list on page functions
Changed urls in readme, point to the website now
Some urls added to the docs index page
Removed `require('mathjs')` here and there in the docs
Referring to downloads page to install/download math.js
Renamed import.md to extension.md
Created a separate page Unit reference
Created a separate reference page with constants