Add validation profile and input sanitation

[ielis]

Add input sanitation.

The commands now use --validation-policy to choose from MINIMAL, LENIENT and STRICT input validation.

The minimal validation places the most rudimentary requirements and does not try to fix the inputs.

The lenient validation runs unless a serious issue (error) is found in the input. The examples of errors include:

• term is both present and excluded
• term is present and ancestor is excluded
• path to VCF does not point to a readable file
• sample ID is missing and the VCF file is multi-sample)

The less severe issues are fixed. The fixes include

• removing duplicate terms
• removing terms that are not descendants of Phenotypic abnormality
• removing ancestors of present terms
• removing descendants of excluded terms

The strict validation requires the input to be impeccable - no errors and no warnings.

The documentation has been updated with a new section.

The user can use --dry-run option to check if the input validates.

[ielis]

Needs phenol 2.0.5 (unreleased).

[ielis]

Fixes #637