add changes to sqlite_ex and some new files

sqlite_ex.h

@@ -11,6 +11,8 @@
 #define SELECT_ALL_TABLES "select * from sqlite_schema where type = 'table';"
 #define SELECT_TWNTH_DAY "select * from twnth_day;"
 #define SELECT_CURRENT_COSTS "select * from costs where id = ?;"
+#define INSERT_MEASUREMENT "insert into measurements (gas, water, electricity, costs) values (?, ?, ?, 1);"
+#define CALCULATION_FORMAT "%s: %d - %d = %f * %f = %f\n"
 #define STR_SIZE 11
 
 typedef struct tm Datetime;