Introduce a helper to obtain both the magnitude of a vector and the
corresponding normalized vector. Use it to capture both values as const
when possible.
Players are not robots, but the show-path cheat tried to pretend they
are, and triggered a BUG warning[1] when looking up robot information
from the player object. Fix this by passing in the robot_info when the
caller is providing a robot, and a named `nullptr` value (as
`create_path_unused_robot_info`) when the caller is providing a
non-robot object.
[1] As below, but repeated many times
```
similar/main/ai.cpp:1905: BUG: object 0x555555858550 has type 4, expected 2
similar/main/ai.cpp:1974: BUG: object 0x555555858550 has type 4, expected 2
```
If exactly one object will always be needed, use an overload that
returns the object id. Otherwise, use an overload that only returns
whether at least one object was created. This simplifies callers that
always request exactly one object.
Iterating over it returns each side number in turn. This allows
converting many loops of the form:
```
for (int i = 0; i < MAX_SIDES_PER_SEGMENT; ++i)
```
to the compact form:
```
for (const auto i : MAX_SIDES_PER_SEGMENT)
```
The compact form brings the usual benefit of range-based for: delegating
iteration to the compiler prevents the loop body from skipping a step,
and makes clear in the code that this is the case.
gcc treats the intervening lines since the last `if` as sufficient to
recognize this as not misleading. clang does not. Change the indent to
calm clang.
Define separate enum values for rotation data in both the high bits,
where it is usually kept, and the low bits, where it is sometimes used
for math or comparisons.
Define an enum value to represent the composite of the index and the
rotation, since the composite is not suitable for use as an array
subscript. Add helper functions to extract the component pieces.
A declaration is useful if it declares an external function. A static
inline declaration, if not followed by the definition later in the same
translation unit, will not be useful. Remove such declarations, and
rely on using the definition as a declaration for those files that
actually call partial_range() or similar functions.
