support numeric and alphanumeric qualifiers

1. Small fix to parse numeric qualifiers (e.g. 1.2.3-4). Please see testQualifierDashNumeric
2. Number-aware comparison of qualifiers with numbers (e.g. 1.2.3-r10 is greater than 1.2.3-r9). Made use of Stephen Friedrich's BSD licensed Strings utility for this. Please see testCompareQualifier and testCompareQualifierNumeric

thanks
sriram