Raise Liquid::ArugmentError when condition has wrong usage

Condition now raises ::ArgumentError when built wrongly.
This patch make it raise Liquid::ArgumentError instead
to indicate a liquid markup error instead of ruby error.
Remove unnecessary blank? code
Merge pull request #389 from Shopify/remove_unnecessary_blank_stuf

Remove unnecessary blank? code
Fixing regression from block delimiter enhancement
Merge pull request #393 from Shopify/fix_block_delimiter

Fixing regression from block delimiter enhancement
Merge pull request #341 from curebit/comparation_argument_error

Raise Liquid::ArugmentError when condition has wrong usage
remove .flatten on standard filters
add a input iterator to standard filter
Array is a Enumerable
Fix broken standardfilter test
add flatten filter
Fix regression on map
add more legacy tests
Forgot an error message case
Merge pull request #395 from Shopify/fix_block_delimiter

Forgot an error message case
remove unnecessary flatten filter
Exception handling for humans

Ability to pass exception_handler as a block to #render
and provide whatever behavior you want on handling exceptions

https://github.com/Shopify/liquid/pull/254
Merge pull request #397 from Shopify/bogdan-excetion-handling-for-humans

Excetion handling for humans (2)
Merge pull request #240 from Shopify/remove_flatten

remove .flatten on standard filters
Update History log
Bring latest History from 2-6-stable and 2-5-stable