Working test cases for the sophisticated matrix library example from the manual

Fixed the dot operator when used within return types (see tgenericdotrettype)
Fixed the matching of generic concepts aliases used with the implicit generics style

tests/concepts/matrix.nim

@@ -0,0 +1,15 @@
+type
+  Matrix*[M, N: static[int]; T] = object
+    data: array[M*N, T]
+
+proc `[]`*(M: Matrix; m, n: int): M.T =
+  M.data[m * M.N + n]
+
+proc `[]=`*(M: var Matrix; m, n: int; v: M.T) =
+  M.data[m * M.N + n] = v
+
+# Adapt the Matrix type to the concept's requirements
+template Rows*(M: type Matrix): expr = M.M
+template Cols*(M: type Matrix): expr = M.N
+template ValueType*(M: type Matrix): typedesc = M.T
+