Remove pcraster and more

[gnrgomes]

Correction of:

• [Issue timesteps between Stepstart and StepEnd with a 360_day calendar #70]: calculation of the timesteps between StepStart and StepEnd with a 360_day calendar
• Remove PCRaster
• Introduction of variable Relative Humidity to calulate Vapor Pressure
• Validation of the units in the input files configured in the settings file
• New feature that allows to define in the settings file conversion factors to convert input file units
• Other corrections