Small fix for PS and more

- Added menu option for dynamic PI. When PI changes (due fading and another station is received on the same frequency), when dynamic PI is enabled, new PI will be shown. Disadvance of this, is that on weak signals correct received PI can be overwritten by a false PI.

- Smallest font now 1px larger
- When no battery, the icon is not shown.

- PS is now stable when length < 8 characters

- Enabled Stationlist for AM (tuning currently not possible)

src/TEF6686.h

@@ -196,6 +196,7 @@ typedef struct _rds_ {
   bool filter;
   bool underscore;
   bool rdsreset;
+  bool dynamicpi;
 } rds_;
 
 typedef struct _af_ {
@@ -267,4 +268,5 @@ class TEF6686 {
     uint16_t rdsDprevious;
     bool correctpi;
     bool rtABold;
+    wchar_t PStext[9] = L"";           
 };