Fix standalone Lua script screen flicker and improve error messages (#982)

* Relax assumptions about when Lua is called in foreground and background

* Start Lua cycle timer both in foreground and background
Do not assume that background/foreground alternates

* Lua is called at every Standalone GUI cycle instead of 5 Hz
Since Lua preempts every 50 ms or so, the GUI should remain responsive.

* In standalone script, only call Lua once per GUI cycle, to avoid messing up buffer handling.

* Revamped error reporting for Standalone and Telemetry Lua scripts

* Font size for Lua error is reduced from XL to L on color if LCD_W < LCD_H

* In drawTextLines, also possible linebreaks for opening brackets.

* Smaller font for error message on tall color screen

* Make titlebar height match font size on narrow LCD

radio/src/lua/lua_api.h

@@ -113,8 +113,7 @@ enum ScriptState {
   SCRIPT_OK,
   SCRIPT_NOFILE,
   SCRIPT_SYNTAX_ERROR,
-  SCRIPT_PANIC,
-  SCRIPT_FINISHED
+  SCRIPT_PANIC
 };
 
 enum ScriptReference {
@@ -169,10 +168,9 @@ bool luaTask(event_t evt, bool allowLcdUsage);
 void checkLuaMemoryUsage();
 void luaExec(const char * filename);
 void luaDoGc(lua_State * L, bool full);
-void luaError(lua_State * L, uint8_t error, bool acknowledge=true);
 uint32_t luaGetMemUsed(lua_State * L);
 void luaGetValueAndPush(lua_State * L, int src);
-uint8_t isTelemetryScriptAvailable(uint8_t index);
+bool isTelemetryScriptAvailable();
 
 #define luaGetCpuUsed(idx) scriptInternalData[idx].instructions
 #define LUA_LOAD_MODEL_SCRIPTS()   luaState = INTERPRETER_RELOAD_PERMANENT_SCRIPTS