Skipping walls swimming in Half-Life

Water movement code explained by YaLTeR:
1. calculate move end position (just as a vector, no collision checks whatsoever)
2. trace from (this end position + stepsize + 1) to (this end position)
3. if the trace wasn't inside something, use this end position and return
worldspawn wall skipping locations and estimated TAS time saves
blast pit
- (tentacle skip 60s+)
- toxic waste canal into pipe 2s
apprehension
- tram skip 5s
- swimming maze 12s
- (stairs and pistons skip 4s)
residue processing
- hazard pools skip 4s
- canal skip through bottom 9s
forget about freeman
- (sewer to elevator 2s++)
lambda core
- water pipe skip 4s
- (lambda core water into teleporter room 8s)