Hygiene/single code style for all existing macros

[dr-orlovsky]

While being not really important, had to do hygiene of all internal macros (since many of which I re-use in other places) such they now follow the same standard/coding style for all namespace prefixes (i.e. starting with :: followed by a fully-clarified name).

Also added doc strings to some of the macros

[dr-orlovsky]

FYI, have figured out how the macro system works:

• use ::std instead of $crate::std: works well both for internal macros and exported. If $crate::std is used, it will not work in exported macros (compiler error)
• use $crate::core instead of ::core – and you also have to specify pub crate core in lib.rs. ::core is not working with exported macros

[stevenroose]

Is it worth it to have all this verbosity for macros we don't export?

[dr-orlovsky]

What I am sure is that

1. it worth to stick to some defined coding style throughout the code and not switch its arbitrary even within a single macro;
2. be prepared that the code may be forked and maintained by other Bitcoin-related projects outside of the concept of "let's make another wallet [library]" which are not fixed on the idea of limiting their functionality to the set of predefined scripts etc. This means it would be nice to have a library prepared to export macros you don't aim to export now - just not to copy-paste its code into their projects.

[dr-orlovsky]

seems Travis needs reset

[stevenroose]

I restarted the timed out test with cleared caches.

[dr-orlovsky]

I have rebased this onto master. Pls let me know if there any need in this.

[elichai]

I'm for better macro hygiene, it will also ease our life when we will update to edition 2018.
it also reduces ambiguity if you have the same type defined under different modules

[stevenroose]

ack 257ca8e

[elichai]

ACK