| Elektra 0.11.0

`keyIsBelow`

# Problem

There are multiple very similar functions to check the "is below" relation between to keys:

- Replacement `keyIsBelow`
- Replacement `keyIsBelowOrSame`
- Replacement `keyIsDirectlyBelow`

# Constraints

Keep (at least) the same functionality

# Assumptions

# Considered Alternatives

# Decision

Merge `keyIsBelow` with `keyIsBelowOrSame` and `keyIsDirectlyBelow` to create this new API:

int keyIsBelow (const Key * base, const Key * other);
keyIsBelow
int keyIsBelow(const Key *key, const Key *check)
Check if the Key check is below the Key key or not.
Definition keytest.c:138

The replacements for the old functions are:

- old keyIsBelow: `keyIsBelow > 0`
- keyIsBelowOrSame: `keyIsBelow >= 0`
- keyIsDirectlyBelow: `keyIsBelow == 1`

# Rationale

# Implications

# Related Decisions

# Notes