"Mutex" Trait based API

[vitiral]

This is a counter proposal to #14 and aims to be simpler and more future proof.

I have sketched out an implementation which compiles (but is not tested) here:

https://github.com/vitiral/utex/blob/master/src/lib.rs

Reason of need

The embedded ecosystem is very likely to have multiple ways of allocating data, from statically to managed-static to full dynamic. However, most libraries should not care who allocated data -- only that it will not get freed and is not being used by others.

Therefore there is a strong need for a single trait that all of these libraries can use for wrapping the data they return.

Issue at Hand

The existing Buffer API will tie us to the following:

• a specific buffer type and way of representing data
• a lock/unlocking mechanism that can not be easily extended by other crates. For instance, it would be difficult to implement a memory manager using the Buffer API

This design aims to address this by providing a Mutex trait which can then be implemented in any way we please. Something like the Buffer proposed would be free to implement this trait and then be used for the full API.

[japaric]

I'm closing this since #13 was also closed

[vitiral]

sorry, I should have closed this before. Thanks!