Verify data table sizes with table_width and assert_table_length macros

This was discussed in #706

It also uncovered some off-by-one issues with defining some constants.

A few structs now use rsreset/_RS to define their offset constants, as discussed in #739

data/phone/non_trainer_names.asm

@@ -1,11 +1,13 @@
 NonTrainerCallerNames:
-; entries correspond to PHONECONTACT_* constants
+; entries correspond to PHONECONTACT_* constants (see constants/trainer_constants.asm)
+	table_width 2, NonTrainerCallerNames
 	dw .none
 	dw .mom
 	dw .bikeshop
 	dw .bill
 	dw .elm
 	dw .buena
+	assert_table_length NUM_NONTRAINER_PHONECONTACTS + 1
 
 .none:     db "----------@"
 .mom:      db "MOM:@"