Print the unchunked_ext_msg bit in get_source_cap

A new bit was added to the Source Fixed Supply PDO in PD 3.0, saying
whether the source supports unchunked extended messages.  It's not
really relevant to the PD Buddy Sink since it itself doesn't support
them, but users might want to know and it's very little work to print
it, so now it does.

docs/console_config.md

 # PD Buddy Sink Serial Console Configuration Interface
 
-Version 1.2.0-dev.1, 2018-01-10
+Version 1.2.0-dev.1, 2018-01-13
 
 The PD Buddy Sink can be put into setup mode by holding the Setup button while
 plugging it into a computer.  In this mode, the device runs a configuration
 The `dual_role_data` field holds the value of the PDO's Dual-Role Data bit
 (B25).  If this field is not present, its value shall be assumed 0.
 
+#### unchunked_ext_msg
+
+The `unchunked_ext_msg` field holds the value of the PDO's Unchunked Extended
+Messages Supported bit (B24).  If this field is not present, its value shall be
+assumed 0.
+
 #### peak_i
 
 The `peak_i` field holds the value of the PDO's Peak Current field (B21-20), in

lib/include/pd.h

 #define PD_PDO_SRC_FIXED_USB_COMMS (1 << PD_PDO_SRC_FIXED_USB_COMMS_SHIFT)
 #define PD_PDO_SRC_FIXED_DUAL_ROLE_DATA_SHIFT 25
 #define PD_PDO_SRC_FIXED_DUAL_ROLE_DATA (1 << PD_PDO_SRC_FIXED_DUAL_ROLE_DATA_SHIFT)
+#define PD_PDO_SRC_FIXED_UNCHUNKED_EXT_MSG_SHIFT 24
+#define PD_PDO_SRC_FIXED_UNCHUNKED_EXT_MSG (1 << PD_PDO_SRC_FIXED_UNCHUNKED_EXT_MSG_SHIFT)
 #define PD_PDO_SRC_FIXED_PEAK_CURRENT_SHIFT 20
 #define PD_PDO_SRC_FIXED_PEAK_CURRENT (0x3 << PD_PDO_SRC_FIXED_PEAK_CURRENT_SHIFT)
 #define PD_PDO_SRC_FIXED_VOLTAGE_SHIFT 10

src/shell.c

         chprintf(chp, "\tusb_suspend: %d\r\n", tmp);
     }
 
-    /* Unconstrained power */
+    /* Unconstrained Power */
     tmp = (pdo & PD_PDO_SRC_FIXED_UNCONSTRAINED) >> PD_PDO_SRC_FIXED_UNCONSTRAINED_SHIFT;
     if (tmp) {
         chprintf(chp, "\tunconstrained_pwr: %d\r\n", tmp);
     }
 
-    /* USB communications capable */
+    /* USB Communications Capable */
     tmp = (pdo & PD_PDO_SRC_FIXED_USB_COMMS) >> PD_PDO_SRC_FIXED_USB_COMMS_SHIFT;
     if (tmp) {
         chprintf(chp, "\tusb_comms: %d\r\n", tmp);
     }
 
-    /* Dual-role data */
+    /* Dual-Role Data */
     tmp = (pdo & PD_PDO_SRC_FIXED_DUAL_ROLE_DATA) >> PD_PDO_SRC_FIXED_DUAL_ROLE_DATA_SHIFT;
     if (tmp) {
         chprintf(chp, "\tdual_role_data: %d\r\n", tmp);
     }
 
-    /* Peak current */
+    /* Unchunked Extended Messages Supported */
+    tmp = (pdo & PD_PDO_SRC_FIXED_UNCHUNKED_EXT_MSG) >> PD_PDO_SRC_FIXED_UNCHUNKED_EXT_MSG_SHIFT;
+    if (tmp) {
+        chprintf(chp, "\tunchunked_ext_msg: %d\r\n", tmp);
+    }
+
+    /* Peak Current */
     tmp = (pdo & PD_PDO_SRC_FIXED_PEAK_CURRENT) >> PD_PDO_SRC_FIXED_PEAK_CURRENT_SHIFT;
     if (tmp) {
         chprintf(chp, "\tpeak_i: %d\r\n", tmp);
     tmp = (pdo & PD_PDO_SRC_FIXED_VOLTAGE) >> PD_PDO_SRC_FIXED_VOLTAGE_SHIFT;
     chprintf(chp, "\tv: %d.%02d V\r\n", PD_PDV_V(tmp), PD_PDV_CV(tmp));
 
-    /* Maximum current */
+    /* Maximum Current */
     tmp = (pdo & PD_PDO_SRC_FIXED_CURRENT) >> PD_PDO_SRC_FIXED_CURRENT_SHIFT;
     chprintf(chp, "\ti: %d.%02d A\r\n", PD_PDI_A(tmp), PD_PDI_CA(tmp));
 }