Easyeeg

- Now `Time_frequency` supports the power difference between two conditions
- Fixed a issue when plot the heatmap

- Removed `time_group` index which are unnecessary in Analyzed_Result
- Refine X axis in figure
- Improved the compatibility of save() and load() of Analyzed_Result
- New algorithm `frequency_topography()`. Now we can calculate the topography of frequency.
- New method `convert()` in module `Basic`

- MASSIVE amount of changes
- Altered the package name to "easyEEG"

- First to public release. Merry Xmax!