Release 0.2.0 version

Update

• New models including tomotopy.CTModel and tomotopy.SLDAModel were added into the package.
• A new parameter option rm_top was added for all topic models.

Bug Fixed

• The problems in save and load method for PAModel and HPAModel were fixed.
• An occassional crash in loading HDPModel was fixed.
• The problem that ll_per_word was calculated incorrectly when min_cf > 0 was fixed.