Release Version 0.5.0: Stable Release

Skipped 0.4.0.

Major Changes:

• Minor changes to arguments for functions and classes
• Major changes to grid_sample function. Finally got around to compare the implemented grid_sample with some baselines such as cv2.remap and scipy's map_coordinates. Wrote a lot of test codes to make sure that this implementation comes close to them as much as possible. Also compared numpy and torch's grid_sample and made sure they were close too.
• mypy compatible (sort of). This still needs work, but it's a start.
• Revamp to test codes (pytest). Back then I only checked if it ran, but now I made test codes (and benchmark codes) to test most of the functions (+ alpha). In the future, I might add codecov.