Better strtoul and printf precision for strings

[diondokter]

I should have contributed earlier because that would've saved people some work.
Anyways, I worked on this while updating nrfxlib and making a new async wrapper around it.

I think the current strtoul implementation is wrong. It only takes a single string parameter while the real function has more: https://cplusplus.com/reference/cstdlib/strtoul/

My implementation is a port from a C implementation I found (I believe it was from this one: https://github.com/gcc-mirror/gcc/blob/master/libiberty/strtoul.c)

Also I made string precision support for the printf function.
Nrfxlib has a new API for AT commands where it calls printf. I want the users to not have to care about putting in a null byte after all their AT command strings. So I need a way to print up until a given length instead of up until a null byte. See the usage here: https://github.com/diondokter/nrf-modem/blob/c4a01f5062b86771df57fc283a5d4c82f24eec39/src/at.rs#L163-L169

[jonathanpallant]

As each implementation can come from a different place, the general rule is to put the licence information into each file.

You've removed my copyright and Blue Oak Model Licence statement from strtoul, which is fair as you've also removed the implementation. But you've stated above the implementation is copied from libiberty, which has licence text at the top that you need to follow. Specifically:

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. [rescinded 22 July 1999]
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.

I am not a lawyer, but doing a source conversion from C to Rust and publishing the result would appear to me to be a copyright violation unless performed within the licence terms offered.

[jonathanpallant]

The licence also needs to be added to LICENCES.md

[diondokter]

I'm also not a lawyer, so I'll just add the license info

[diondokter]

Oh well, this is strange. Atoi fails on Linux but not on my Windows...

[diondokter]

Should be good now

[jonathanpallant]

SPACE_CHARACTERS.contains(&argument) would match the other functions.

[diondokter]

True, fixed it

[diondokter]

Oh, whoops, forgot to fmt

[diondokter]

So ehh, do I have to merge this? It's been approved, but I don't see a button for me to click. Or does somebody else need to?

[jonathanpallant]

I guess I need to?