Creates and displays a waitbar depending on the file position indicator(FID).
Due to the fact that the waitbar updates automatically via timer function
it is not necessary to update it manually in each cycle of the loop.

H = FWAITBAR(FID) initializes the waitbar due to file identifier
obtained from FOPEN. The length of the bar will compute due to
file position indicator obtained from FTELL.
The handle to the waitbar figure is returned in H.

FWAITBAR(FID,'message') initializes the wait bar with a specified
message.

FWAITBAR is typically used outside a FOR/WHILE loop that performs a
lengthy operation with readout of files.

Example
fid=fopen('fopen.m');
fwaitbar(fid);
while 1
tline = fgetl(fid);
if ~ischar(tline), break, end
disp(tline)
pause(0.05)
end
fclose(fid);