rtknavi: enable and disable the start button

rather than just changing its visibility as the output stream and log
stream change methods test if the start button is enabled and were not
operating when started. Same issue on the windows and Qt apps.

Author: ourairquality

app/qtapp/rtknavi_qt/navimain.cpp

@@ -1253,6 +1253,7 @@ void MainWindow::serverStart()
     updatePlot();
 
     ui->btnStart->setVisible(false);
+    ui->btnStart->setEnabled(false);
     ui->btnOptions->setEnabled(false);
     ui->btnExit->setEnabled(false);
     ui->btnInputStream->setEnabled(false);
@@ -1293,6 +1294,7 @@ void MainWindow::serverStop()
     for (i = 0; i < 3; i++) delete[] cmds[i];
 
     ui->btnStart->setVisible(true);
+    ui->btnStart->setEnabled(true);
     ui->btnOptions->setEnabled(true);
     ui->btnExit->setEnabled(true);
     ui->btnInputStream->setEnabled(true);

app/winapp/rtknavi/navimain.cpp

@@ -1302,6 +1302,7 @@ void __fastcall TMainForm::SvrStart(void)
     UpdatePos();
     UpdatePlot();
     BtnStart    ->Visible=false;
+    BtnStart    ->Enabled=false;
     BtnOpt      ->Enabled=false;
     BtnExit     ->Enabled=false;
     BtnInputStr ->Enabled=false;
@@ -1334,6 +1335,7 @@ void __fastcall TMainForm::SvrStop(void)
     rtksvrstop(&rtksvr,(const char **)cmds);
 
     BtnStart    ->Visible=true;
+    BtnStart    ->Enabled=true;
     BtnOpt      ->Enabled=true;
     BtnExit     ->Enabled=true;
     BtnInputStr ->Enabled=true;