Rename machine_(u)int_t to mp_(u)int_t.

See discussion in issue #50.
diff --git a/py/objfun.h b/py/objfun.h
index f607a5e..cc8035e 100644
--- a/py/objfun.h
+++ b/py/objfun.h
@@ -26,15 +26,15 @@
 
 typedef struct _mp_obj_fun_bc_t {
     mp_obj_base_t base;
-    mp_obj_dict_t *globals; // the context within which this function was defined
-    machine_uint_t n_pos_args : 16;     // number of arguments this function takes
-    machine_uint_t n_kwonly_args : 16;  // number of arguments this function takes
-    machine_uint_t n_def_args : 16;     // number of default arguments
-    machine_uint_t has_def_kw_args : 1; // set if this function has default keyword args
-    machine_uint_t takes_var_args : 1;  // set if this function takes variable args
-    machine_uint_t takes_kw_args : 1;   // set if this function takes keyword args
-    const byte *bytecode;   // bytecode for the function
-    qstr *args;             // argument names (needed to resolve positional args passed as keywords)
+    mp_obj_dict_t *globals;         // the context within which this function was defined
+    mp_uint_t n_pos_args : 16;      // number of arguments this function takes
+    mp_uint_t n_kwonly_args : 16;   // number of arguments this function takes
+    mp_uint_t n_def_args : 16;      // number of default arguments
+    mp_uint_t has_def_kw_args : 1;  // set if this function has default keyword args
+    mp_uint_t takes_var_args : 1;   // set if this function takes variable args
+    mp_uint_t takes_kw_args : 1;    // set if this function takes keyword args
+    const byte *bytecode;           // bytecode for the function
+    qstr *args;                     // argument names (needed to resolve positional args passed as keywords)
     // the following extra_args array is allocated space to take (in order):
     //  - values of positional default args (if any)
     //  - a single slot for default kw args dict (if it has them)