KT-151 Inherit visibility when overriding

#KT-151 Fixed

Visibilities.INHERITED constant added (occurs only during resolve), changed after overridden descriptors resolve
Fake descriptors are created for invisible properties as well (is necessary for better error reporting)

compiler/testData/diagnostics/tests/scopes/VisibilityInheritModifier.jet

@@ -18,7 +18,7 @@ open class D {
 }
 
 class E : D() {
-    internal <!NOTHING_TO_OVERRIDE!>override<!> fun self() = this
+    internal <!CANNOT_OVERRIDE_INVISIBLE_MEMBER!>override<!> fun self() = this
 
     fun test() {
         val <!UNUSED_VARIABLE!>s<!> : E = self()
@@ -31,7 +31,11 @@ open class F {
 }
 
 class G : F() {
-    <!CANNOT_CHANGE_ACCESS_PRIVILEGE!>override<!> fun protected_fun() {}
+    override fun protected_fun() {}
+}
+
+fun test_fun_stays_protected(g: G) {
+    g.<!INVISIBLE_MEMBER!>protected_fun<!>()
 }
 
 //------------
@@ -57,11 +61,11 @@ trait T {
 }
 
 open class L : T {
-    <!CANNOT_WEAKEN_ACCESS_PRIVILEGE!>override<!> fun foo() {}
+    override fun foo() {}
 }
 
 class M : L() {
-    internal override fun foo() {}
+    <!CANNOT_WEAKEN_ACCESS_PRIVILEGE!>internal<!> override fun foo() {}
 }
 //---------------
 trait R {

compiler/testData/diagnostics/tests/scopes/kt151.jet

@@ -0,0 +1,40 @@
+//KT-151 Inherit visibility when overriding
+package kt151
+
+open class A {
+    protected open fun x() {}
+}
+
+class B : A() {
+    override fun x() {} // No visibility modifier required
+}
+
+fun test(b: B) {
+    b.<!INVISIBLE_MEMBER!>x<!>()
+}
+
+
+//more tests
+open class C {
+    internal open fun foo() {}
+}
+
+trait T {
+    protected fun foo() {}
+}
+
+class D : C(), T {
+    <!CANNOT_CHANGE_ACCESS_PRIVILEGE!>protected<!> override fun foo() {}
+}
+
+class E : C(), T {
+    <!CANNOT_CHANGE_ACCESS_PRIVILEGE!>internal<!> override fun foo() {}
+}
+
+class F : C(), T {
+    <!CANNOT_WEAKEN_ACCESS_PRIVILEGE!>private<!> override fun foo() {}
+}
+
+class G : C(), T {
+    override fun foo() {}
+}