fixed: conflict correctly detected with alteration operations

In this example the conflict was not detected:

trait TFirst {
	String s() { return ""; }
}

trait T1 uses TFirst[alias s as s2] {
	
}

trait T2 uses T1[alias s as s2] {
	
}

Change-Id: Iab56f63fee84fdd66bdc54f9935fa4037dd8c63d
test for missing field with correct type

after renaming

Change-Id: I461e3de61ba3752d8b3232124e4aaca850d87aa9
avoid NPE in getter/setter management

Change-Id: Iedd1c891f0cd51490d6de20fd6a2a3d3453972fc
field checkConflicts in the presence of generic types

Change-Id: I96e876abd1d32828576d42f645d215e5fc9c0ab8
required method checkConflicts in the presence of generic types

Change-Id: Ia8214b361a4c7d148d2f48364a18768bddcbcdb3
removed conflictsWith(JvmOperation,JvmOperation) 

Change-Id: I1b4935a978b4001188f4ddf95ea40cf664113c3a
always use the context for type conformance

Change-Id: I7283f6d53f362a3f2a4bc47720a9b73308409957
Outline: generic methods of interface with type params instantiated

Change-Id: Icf20707cce461d25057d304f8f0cc22883e69814