defined classId for TextType (avoid NPE for missing classId)
AI-581 - generalized expression stuff (preparations to boolean expression  evaluation for skip logic)

Conflicts:
	server/src/main/java/org/activityinfo/core/shared/expr/PlaceholderExpr.java
	server/src/main/java/org/activityinfo/core/shared/expr/functions/ArithmeticFunctions.java
	server/src/main/java/org/activityinfo/legacy/shared/impl/GetSitesHandler.java