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

See discussion in issue #50.
diff --git a/py/qstr.h b/py/qstr.h
index 9803e67..0d9db19 100644
--- a/py/qstr.h
+++ b/py/qstr.h
@@ -39,13 +39,13 @@
     MP_QSTR_number_of,
 };
 
-typedef machine_uint_t qstr;
+typedef mp_uint_t qstr;
 
 #define QSTR_FROM_STR_STATIC(s) (qstr_from_strn((s), strlen(s)))
 
 void qstr_init(void);
 
-machine_uint_t qstr_compute_hash(const byte *data, uint len);
+mp_uint_t qstr_compute_hash(const byte *data, uint len);
 qstr qstr_find_strn(const char *str, uint str_len); // returns MP_QSTR_NULL if not found
 
 qstr qstr_from_str(const char *str);
@@ -56,7 +56,7 @@
 byte* qstr_build_start(uint len, byte **q_ptr);
 qstr qstr_build_end(byte *q_ptr);
 
-machine_uint_t qstr_hash(qstr q);
+mp_uint_t qstr_hash(qstr q);
 const char* qstr_str(qstr q);
 uint qstr_len(qstr q);
 const byte* qstr_data(qstr q, uint *len);