Bad grammar for field access operator

[Roly Perera]

In elem city.name country.cities, the two tokens after the . parse as the application name country. Allowing an arbitrary expression as the field access qualifier doesn’t really make sense as it needs to be something that binds tightly to the dot (just a variable name would do, if that doesn’t mean rethinking the current approach to parsing field access).

• Regression test
• Migrate new test from scratchpad to misc_cases
• Migrate anomalous cases (lambda, ifElse, matchAs and defsExpr) from simpleExpr to appChain
• Extract opTreeLeaf from appChain
• Fix projection grammar
• Fix problem with prettyprinting projections revealed by corrected grammar