Allow imports, val, def and subtemplates in body of if/else if/else

[mkurz]

Related:

• Support for variables via [lazy] val keywords #1071
• Add support for @var myVariable = ... #1088

[mkurz]

As expected the tests fail as as currently imports, val, def and subtemplates are not allowed in if/else if/else bodies.

[info]   play.twirl.compiler.test.Helper$CompilationError: illegal start of simple expression