Deliberate blocking UploadAndSerial() implementation

Issue stevearc#52

Author: elig0n

autoload/arduino.vim

@@ -601,10 +601,14 @@ function! arduino#Serial() abort
 endfunction
 
 function! arduino#UploadAndSerial() abort
+  " Since 'terminal!' is non-blocking '!' must be used to provide this functionality
+  let termBackup = s:TERM
+  let s:TERM = '!'
   let ret = arduino#Upload()
   if ret == 0
     call arduino#Serial()
   endif
+  let s:TERM = termBackup
 endfunction
 
 " Serial helpers {{{2