write_cout! fix

[zrzka]

DON'T MERGE as it needs to be rebased after all other PRs will be merged (if they will be) and there will be more occurrences of unused std::io::Write imports.

• write_cout! returns number of written bytes
• Terminal::write returns number of written bytes (result of write_cout!)
• execute! macro is a bit simpler
• Remove unused std::io::Write imports

NEW

• Fixes rest of the _cursor & _style to make the cargo test --all --exclude crossterm_winapi pass (didn't check _winapi yet)

Fixes #202

[zrzka]

Or there's 2nd variant of the write_cout! which does use write_all instead of write.

The 1st variant with write can fail, can write part of the buffer only, can return interrupted, which is not an error basically, etc.

[TimonPost]

Thanks, Looks good to me! Still a WIP?

[TimonPost]

Yea, definately better :)

[zrzka]

Yeah, still WIP. Waiting for other PRs to rebase & I didn't go through examples, etc. to check if there is/isn't an unused import.

[zrzka]

Will fix these conflicts with rebase when the #211 & #207 will be merged.

[zrzka]

@TimonPost rebased, added more fixes (see first comment) and finally the whole cargo test --all --exclude crossterm_winapi is passing on my computer. Will continue with 2018 + examples collisions + other cleanup in another branch.