Features:

math helper, similar to select that support math operation and branching
size helper
contextDump helper for debugging
Documentation/ tutorial for the LinkedIn fork of dust (https://github.com/linkedin/dustjs/wiki/Dust-Tutorial)

Bugs Fixes

Fix the {:else} case in the #sections for empty/non existent arrays. Keep it consistent with how
? behaves.
Fix "this" value in anonymous functions

Misc

Moved the helpers code to its own repo - dustjs-helpers
Add more unit test and code coverage
deprecate usage of if helper