Modernize loops by using the `for(type variable : container)` syntax.
Some loops were trivial to fix, whereas others required more attention
to avoid semantic changes. I couldn't address all old-style loops, so
this commit doesn't enable the `modernize-loop-convert` rule.
Although Clang-Tidy's auto-fixer prefers to use `auto` for the loop
variable declaration, I made as many declarations as possible explicit.
To me this increases local readability, as you don't need to fully
understand the container in order to understand the loop variable type.
No functional changes.
Note that possibility to pass the new ID pointer as parameter was kept,
as this is needed for some rather specific cases (like in depsgraph/COW,
when copying into already allocated memory).
Part of T71219.
Surrounding includes with an 'extern "C"' block is not necessary anymore.
Also that made it harder to add any C++ code to some headers, or include headers
that have "optional" C++ code like `MEM_guardedalloc.h`.
I tested compilation on linux and windows (and got help from @LazyDodo).
If this still breaks compilation due to some linker error, the header containing
the symbol in question is probably missing an 'extern "C"' block.
Differential Revision: https://developer.blender.org/D7653
This moves the `alembic`, `avi`, `collada`, and `usd` modules into a common
`io` directory.
This also cleans up some `#include "../../{somedir}/{somefile}.h"` by
adding `../../io/{somedir}` to `CMakeLists.txt` and then just using
`#include "{somefile}.h"`.
No functional changes.
