add rkyv support

[zyansheep]

For some reason github closed the old PR while I was trying to merge master into the old pr. Should've used rebase!

[zyansheep]

@cuviper Any way this can get merged? https://github.com/dimforge/nalgebra/pull/1128 is blocking on this...

[zyansheep]

@cuviper I have made the changes requested :)

[sebcrozet]

Is there any update on this PR? I merged https://github.com/dimforge/nalgebra/pull/1128 without Complex support in the mean time.

[cuviper]

OK, let's go!

bors r+

[bors[bot]]

Build failed:

• Test (1.36.0)

[cuviper]

Bah, libm published new versions with a higher MSRV. I'll deal with that...

[cuviper]

bors r+

[bors[bot]]

Canceled.

[cuviper]

bors r+

[bors[bot]]

Build succeeded:

• Format
• No Std
• Test (1.31.0)
• Test (1.36.0)
• Test (1.54.0)
• Test (beta)
• Test (nightly)
• Test (stable)

[cuviper]

This is published in 0.4.3.