TACS support (variations added to AMPS code)

These are:

- Bandwidth only 25 KHz, so lower deviations
- Data rate only 8000 KHz
- SID is called AID (Area ID)
- MIN1 coding is different

src/amps/main.h

@@ -0,0 +1,5 @@
+
+extern const int tacs;
+
+int main_amps_tacs(int argc, char *argv[]);
+