Support ability to specify that multiple generic type arguments must be distinct

[Alex]

Title currently sucks but the meaning is conveyed in some way or another

Functionality Design

This feature enables the end user to prevent usage of a type with type arguments that may match some criteria, with regards to other type arguments. For example, the currently considered possibilities are:

• Different type arguments (T1 != T2)
  • Example: C<T1, T2> may be specified in a way where replacing both T1 and T2 with the same type argument is prevented
• Non-related type arguments (T1 must not inherit T2)
  • Example: C<T1, T2> may be specified in a way where replacing T1 with a type that inherits T2 is prevented
  • Could also further specify that it would only check class inheritance tree, disregarding potentially mathcing interfaces
• Type arguments' size must match or be related (sizeof(T1) == a * sizeof(T2))
  • Example: C<T1, T2> may be specified in a way where T1's size is equal to that of T2, or a fixed multiple of it
• Type arguments both matching the same special constraints (class, struct, unmanaged)
  • Example: C<T1, T2> requires that both T1 and T2 suit either the class, the struct, or the unmanaged constraint
  • Consider applying this to more other special constraints like notnull, new() (could be adjusted by the time shapes arrive)

API Design

TODO