Pysummarizedexperiment

- Added boxplot and pca method for common workflows
- Added functionality to both import and export long dataframes
- Added validation for adding a new assay
- Added option for requesting the memory size of the object
- Added default metadata 'DateTime'
- Expanded example Jupyter notebook
- Changed style of documentation to Google style

- Documented class and methods

- Reorganized folders for installing and importing
- Added option to export to long format
- Added more examples

- Initial commit