Allow carriage return and tabs.

[mathijs81]

After upgrading handlebars, some of our templates stopped working.
We tracked it down to carriage returns and tabs being part of identifiers now.

This led to some helpers not working anymore, for instance:

{{helper param1="something"
<tab><tab>param2="something else"}}

This change fixes that (and adds a test to check that the parse tree of various ways to format this are the same).

[codecov-io]

Codecov Report

Merging #699 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #699   +/-   ##
=========================================
  Coverage     87.33%   87.33%           
  Complexity      841      841           
=========================================
  Files            78       78           
  Lines          3023     3023           
  Branches        411      411           
=========================================
  Hits           2640     2640           
  Misses          261      261           
  Partials        122      122

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[coveralls]

Coverage remained the same at 91.366% when pulling 1eaa930 on mathijs81:master into 91d8df2 on jknack:master.

[mathijs81]

Is anybody looking at this?

[jknack]

hey, sorry for late response. I copy your work and added it manually.

Thanks