Block with snow

[daretmavi]

Describe the bug
Villager can not jump on Block with snow on it.

To Reproduce
0. Generate word with snow (like Seed 6422333087495876490, V7 generator)

1. Create villager and let her to follow you
2. Get on the block with snow - villager is just standing, not jumping
3. Remove the snow from the block - villager is following you again

Expected behavior
Ignore snow and just jump on it.

Desktop (please complete the following information):

• Minetest version: 5.2.0
• Other mods activated: smart inventory

[theFox6]

I could actually reproduce this failure.
I experienced this problem when the villager is standing on a snow cover and trying to jump up one block onto another snow cover.

The problem is due to the simple obstacle detection.
The villager checks if there is an obstacle in front of him, if there is one the villager jumps.
But only if the block above the one in front of him is not an obstacle.
The snow cover is a collidable block, this means that the villager considers the height too large to jump.

To properly detect obstacles the villager would have to consider the actual altitude and the nodeboxes and orientations of three blocks in front of him.
The one right in front, the one above and the one above that one.
This may slightly affect the performance.

I will try to add the detection. However adding this feature may take a bit of time.