Add a functional argument to decide whether skip clip before final result.

[Leoooo333]

Hi, I want to use the equilib without clip process before the final result. Here I include an function argument clip_output: bool to decide whether do clip. I tested it on HDR image successfully on Equi2Pers. It's compatible to the previous equilib. To disable clip, just include clip_output = False when doing Equi2Pers. Here is the test case of crop a perspective view from the .exr file which refer to a equir HDR image. In this pull request, I just modify the Equi2Pers part, but you can disable clip to Equi2other format the same as this.

img= cv2.imread(PATH_TO_EXR_FILE,  cv2.IMREAD_UNCHANGED)
from equilib import Equi2Pers
v_rad, u_rad = (0, 0)
fov = 120
equi2pers = Equi2Pers(height=960, width=960, fov_x=fov, mode="bilinear")
pers_image = equi2pers(img, rots={"roll": 0, "pitch": v_rad, "yaw": u_rad}, clip_output=False)