FIX #3939: Import TXT resource records with semicolons and respecting it's case

I replace the RegEx that ISPConfig uses to see if it must truncate the line sith a semicolon.

Now the line does not get truncated if the semicolon is between quotes.

Later, when ISPConfig lower the case of the parts of the lines, I changed the condition, so it does not lower the case of parts that begin or finish with quotes (First and last part or TXT RRs) or it has a semicolon, meaning it was between quotes and wasn't replaced previously.