Context: recursively inject the context

For each non-Service, non-Context, non-primitive @parameter, check
whether it is already assigned a value, and if so, inject the context
into that value.

This makes it much easier to compose a class whose member fields also
need to know the context at the same time as the containing class.

See next commit for an example.

Author: ctrueden

src/main/java/org/scijava/Context.java

@@ -471,6 +471,11 @@ else if (Context.class.isAssignableFrom(type) && type.isInstance(this)) {
 				// populate Context parameter
 				ClassUtils.setValue(f, o, this);
 			}
+			else if (!type.isPrimitive()) {
+				// the parameter is some other object; if it is non-null, we recurse
+				final Object value = ClassUtils.getValue(f, o);
+				if (value != null) inject(value);
+			}
 		}
 		catch (final Throwable t) {
 			handleSafely(t);