Make M*LIB stricter for INIT_MOVE operator:

* either the default INIT_MOVE operator works ('=')
* either an INIT_MOVE method is defined
* or it is disabled.
As a consequence, fix usage of testobj_t and mpz_t in the repository

The emulation layer of INIT_MOVE using INIT_SET+CLEAR is removed:
it wasn't working correctly with the local memory context
(INIT_MOVE doesn't need any local memory context to work,
 whereas INIT_SET/CLEAR does)
Remove macro M_DO_INIT_MOVE as it is now useless and uses M_CALL_INIT_MOVE.

The INIT_MOVE default method no longer sets the old 'src' to '0':
it was useless (it doesn't catch any error) and complicates compiler parsing.

Fix POD & A1 & CSTR & classic oplists definition (missing INIT_MOVE operators).

doc/API.txt

@@ -99,3 +99,5 @@ V0.8.0 : * The prototypes of REALLOC / FREE operators are incompatible:
          * m-buffer push / pop no longer return a bool (it was undocumented)
          * Remove MEMPOOL support from list & R/B tree
          * m-mempool: Header is obsolete (and no longer useful at all as lists & RB Tree no longer can use it. To remove?). Use new M_USE_POOL interface to pass local pool context.
+         * M*LIB becomes stricter for INIT_MOVE: Emulation layer using CLEAR+INIT_SET when missing INIT_MOVE operator has been removed: either default INIT_MOVE operator (operator '=') is working, or a methode is provided for INIT_MOVE or it is disabled.
+          (It's because supporting emulation layer with new memory context parameter was complicated)