Added functionality to read and write instruction bytecode

Uses some bit hacks to quickly check what data type an opcode may have
by shifting down to units then casting it to a data_type_t.
Not very well tested yet, we'll need to see now.

src/base.h

@@ -35,6 +35,14 @@ typedef union
   f64 as_float;
 } data_t;
 
+typedef enum
+{
+  DATA_TYPE_NIL   = 0,
+  DATA_TYPE_BYTE  = 1,
+  DATA_TYPE_WORD  = 3,
+  DATA_TYPE_FLOAT = 5,
+} data_type_t;
+
 #define DBYTE(BYTE)   ((data_t){.as_byte = (BYTE)})
 #define DWORD(WORD)   ((data_t){.as_word = (WORD)})
 #define DFLOAT(FLOAT) ((data_t){.as_float = (FLOAT)})