Suggested changes in Data class attributes

[Many98]

Suggested changes are:

1. get rid of attribute self.match_data (it seems to be redundant and all information there stored are already stored in self.matches)
2. attributes (self.team_index and self.time_data) store team specific data in particular time period so suggestion is rename them in same manner:
   2a. self.team_index is needed attribute but maybe get rid of LL and name it self.LL_data or similar to emphasize its time dependence
   2b. rename self.time_data to self.SL_data (as I see there are only stored seasonal data of specific teams)
   2c. add another attribute (also including time specifi info about particular team for instance self.last_match_data etc. )
3. add another columns to this time specific attributes like goals differences , ratios etc.

[kunzaatko]

1. I thought about doing just that but I think that if it is not so harming to the execution time, we should leave it be, because this dataframe is different in the purpose and the indexing. It stores data about a team and not a match. This way we can easily create a method or manipulate the frame differently in order to produce something like last N matches of team XX or for instance the matches of team XX with team YY. Is it a sufficient argument or do you still think we should get rid of it? (in summary, the self.matches is meant to be a storage attribute from which we later will extract the feature attribute self.match_data).
2. Ok, good point. I will rename it to self.LL_data and self.SL_data (unlike the self.LL_data there will be a multiindex of 'Sea' and 'team_ID' (is it OK?))
   c) I just made some changes that remove the self.last_match_data completely and leave only the self.match_data (this stores the date of the play so we can later easily access the last match result.
3. I encourage you to add any that you would feel usefull! ;)