Added support for 'order_xsp_same_as_headers' to order the execution of ...

Disclaimer: Maybe I am daft and this isn't the reason for my build problems. Also, Perl is not exactly my expertise so advice and criticism are welcomed and appreciated. And..... this is also my first pull request to an open source project, so again, advice and criticism welcome and appreciated.

I was having issues with the build process only successful approximately 1/5 of the time. ./Build test was complaining "Can't find 'boot_example' symbol in /usr/local/lib/perl/5.18.2/auto/example/example.so" when unsuccessful. After observations, I found the only real difference between the successes and failures were the order of which the main.xs build commands were executing. This seems to have fixed the problem.

- Added support for 'order_xsp_same_as_headers' option to order the execution of xspp commands in generated main.xs - will order the xspp build commands in the same order as the headers in the source directory and their dependencies in order of use.
- Tidy up of a few perl critic complaints
- Removed test comments and warns