Roughness multi input

[AliceHarang]

• [x] : Add the possibility to use multiple roughness files
• [x] : Add Test for the multiple roughness files use
• [x] : Add Test for the multiple bathy files
• [x] : Update the automatic testing

Complementary:

• [x] : Add value input for IL/CL
• [x] : Add test for this value input

[AliceHarang]

After creating the test, I observe a weird behavior when the value is 0 (for bathy and roughness).

[CyprienBosserelle]

Would be neat to fix this one as well: #105

[AliceHarang]

I have also finished to add the possibility to have a Continuous Loss and Initial Loss as a constant.