Revert to standard Remy-style row types - we still have presence
polymorphism, but absent fields no longer have types.
minor fix to projection
Merge branch 'master' into sessions

Conflicts:
	compilePatterns.ml
	desugarDatatypes.ml
	desugarDbs.ml
	desugarFuns.ml
	evalir.ml
	generalise.ml
	instantiate.ml
	parser.mly
	query.ml
	sugarTraversals.ml
	sugarTraversals.mli
	sugartoir.ml
	sugartypes.ml
	tests/patterns.tests
	transformSugar.ml
	typeSugar.ml
	typeUtils.ml
	types.ml
	types.mli
Merge branch 'sessions' of github.com:slindley/links into sessions