Fixed the replace() function in string_utilities so that it returns an unmodified input if the pattern to be replaced is not found. Also it is considered a good practice to check for emptyness of a string rather than querying its size.
Fixed the replace() function in string_utilities so that it returns an unmodified input if the pattern to be replaced is not found. Also it is considered a good practice to check for emptyness of a string rather than querying its size.

tridge/jsbsim,airware/jsbsim,pmatigakis/jsbsim,Stonelinks/jsbsim,airware/jsbsim,tridge/jsbsim,airware/jsbsim,Stonelinks/jsbsim,pmatigakis/jsbsim,tridge/jsbsim,tridge/jsbsim,airware/jsbsim,pmatigakis/jsbsim,AEgisTG/jsbsim,hrabcak/jsbsim,Stonelinks/jsbsim,tridge/jsbsim,hrabcak/jsbsim,hrabcak/jsbsim,AEgisTG/jsbsim,pmatigakis/jsbsim,hrabcak/jsbsim,pmatigakis/jsbsim,pmatigakis/jsbsim,hrabcak/jsbsim,Stonelinks/jsbsim,airware/jsbsim,hrabcak/jsbsim,AEgisTG/jsbsim,AEgisTG/jsbsim,hrabcak/jsbsim,tridge/jsbsim,AEgisTG/jsbsim,tridge/jsbsim,AEgisTG/jsbsim,Stonelinks/jsbsim,airware/jsbsim,Stonelinks/jsbsim,AEgisTG/jsbsim,pmatigakis/jsbsim,Stonelinks/jsbsim,airware/jsbsim