@Override
    public String toString() {
        return markInString(markInString(expression, pos, "[]"), markedPos, "<>") + "(pos: " + pos + ")";
    }
Parses text until a 'stopper' char is reached. Places pos after this stopper char and returns parsed text.
Returns null if no stopper char is found

@param stopper               chars to stop parsing at
@param endIsDelim            if true, then 'end-of-expression' is treated like finding a stopper char
@param escapeChar            if not null, then characters escapced with this char will not be considered stopper chars but parsed as literal char
@param escapeDoubledStoppers if true, then doubled up stopper chars will not be considered stoppers but parsed as single literal chars
main/src/main/java/cgeo/geocaching/utils/TextParser.java