Merge pull request #1 from Yuras/master

Crash on incomplete tag
Fix incorrect test for missing tag end marker

Check whether content.indexOf(m_tagEndMarker,...) returned -1
to indicate no matching end marker before adding the marker length.

TEST: TestMustache::testIncompleteTag
Fix infinite loop when processing incomplete sections in tags

If the end tag for a section is not found, do not try to render
the section after recording the error.

fixes #2
Avoid building unit test as an app bundle on Mac
Add additional checks for error conditions

 * Test errors for invalid custom delimiters
 * Check for correct error when a tag start/end mismatch and a missing
   end tag both occur.
 * Add check in Renderer::setError() than an existing error is not being
   overwritten.