Changed the internal 'if' helper such that it can test not only paths/variable names, but also numeric constants.

This will be helpful for subexpressions later, when testing numeric subexpressions return values,

eg: {{#if (eq 0 (mod @index 3))}}

Also added a test for this.
Changed the internal 'if' helper such that it can test not only paths/variable names, but also numeric constants.

This will be helpful for subexpressions later, when testing numeric subexpressions return values,

eg: {{#if (eq 0 (mod @index 3))}}

Also added a test for this.
Added support for subexpressions in helper calls. Not sure if Template.php is the best place to handle subexpressions...
Added testHelperSubexpressions()
Added testHelperSubexpressions()
Fixed indentation / code style
More code style / indentation fixes
Added test for correctness of treatment of brackets inside string arguments ( {{foo '(bar)'}} )
Implemented proper treatment of brackets inside string arguments in subexpressions ( {{foo '(bar)'}} )
local merge of #56 PR. fixes 54