Bug fixes, Modularization and other enhancements

- Modularized the functions so as to maintain them easily. Could be useful when implementing tweets.
- Fixed the previous segfault bug.
- start() function previously used recursion, I set it up as an iteration now so as to save space on stack. Not sure if this is right though.
- Added a license, change it as you please.
- Added a new README, explains the build process, a bit on how it works and other necessary stuff.
- the date compare using strncmp() previously was wrong, I wrote a new function compareTime() for it.
- I finished the substring() function as well. Using it in the program to extract the date string from the <pubdate> tags.
- Added a little makefile.