Revert "45-degree overhang on grips."

This reverts commit 93acff94b6fa2c6ee354162e47a7aef79c3e0016.
Move to 8mm diameter.
Hook is a cone rather than a section of cylinder wall.
Increase fineness.
Set fineness globally.
Refactor hook, throat, grip and narrowing into modules.
Bound hook by outer shell.
Reduce depth of narrowing.