**New Features**:
- Added prepare module with replace_white_dir, las2laz and merge_laz_files function
- Added filtering module with functions for all necessary filters and segmentation (return filter, dem filter, elm filter, outlier filter, ground segmentation and surface segmentation)
- Added modeling module with terrain and surface model functions
**Improvement**:
- Fixed the snow_pc prepare_pc bugs
- Improved the readme and the api documentation for the website