Add HTMLCommons class (for some global HTML tags)
Add PTTCommons class (for global usage)
Add PTTCrawler class (for OOP rearrangement)

- methods: __init__(boardName, startIndex, endIndex), crawl()
Updated some global constants that are needed
Added a few HTML tags that will be used
Finalized initial OOP-version of PTTCrawler
Driver for the OOP-version of PPTCrawler (initially Dien-Yang's pttcrawler.py)
(Ignore last commit) Main driver code for PTTCrawler.
Add class PTTPost. The object class for a single PTT post.
Add PTTPostParser class. Works with class PTTPost
Don't need the original pttcrawler.py by Dien-Yang