GROOVY-3457: Fixing issues in the replacement StreamingTemplateEngine

o The template engine now handles $var style variable reference
o Fixed invalid line numbers reported when template errors were encountered
o Fixed failing execution of the example given in the javadoc...doh
o Improved unit test coverage: added the javadoc example as a spock test,
  added tests for $var expressions, improved coverage for other expressions,
  added test for correct line numbers in exception on template errors
o Improved template exception messaging with three lines of
  context so that the exception message contains the erring lines.
GROOVY-3457: Fixing issues in the replacement StreamingTemplateEngine

o The template engine now handles $var style variable reference
o Fixed invalid line numbers reported when template errors were encountered
o Fixed failing execution of the example given in the javadoc...doh
o Improved unit test coverage:
  - added the javadoc example as a spock test
  - added tests for $var expressions
  - improved coverage for other expressions
  - added test for correct line numbers in exception on template errors
  - added tests to validate evaluation of permutations of adjacent expressions
o Improved template exception messaging with three lines of
  context so that the exception message contains the erring lines.
GROOVY-3457: removing debug logging and fixing indentation
Merge branch 'master' of github.com:mbjarland/groovy-core

Conflicts:
	subprojects/groovy-templates/src/test/groovy/groovy/text/StreamingTemplateEngineSpecification.groovy
Merge pull request #533 from mbjarland/master

GROOVY-3457: Fixing issues in the replacement StreamingTemplateEngine