Support for Windows 10

I'd like to support Linux (check), MacOS (issue #2) and Windows. This issue tracks the last one, which I believe needs some tweaks to the code and maybe a special build.

The first test on Windows 10 fails to build, as reported [here](https://safenetforum.org/t/learning-rust/32089/26?u=happybeing):
```
error[E0433]: failed to resolve: maybe a missing crate `sys`?
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\lib.rs:27:9
|
27 | pub use sys::tty::{is_tty, get_tty};
| ^^^ maybe a missing crate `sys`?

error[E0433]: failed to resolve: maybe a missing crate `sys`?
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\async.rs:5:5
|
5 | use sys::tty::get_tty;
| ^^^ maybe a missing crate `sys`?

error[E0433]: failed to resolve: maybe a missing crate `sys`?
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:29:5
|
29 | use sys::attr::{get_terminal_attr, raw_terminal_attr, set_terminal_attr};
| ^^^ maybe a missing crate `sys`?

error[E0432]: unresolved import `sys`
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:28:5
|
28 | use sys::Termios;
| ^^^ maybe a missing crate `sys`?

error[E0425]: cannot find function `get_tty` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\async.rs:14:36
|
14 | thread::spawn(move || for i in get_tty().unwrap().bytes() {
| ^^^^^^^ not found in this scope

error[E0425]: cannot find function `get_tty` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\async.rs:43:36
|
43 | thread::spawn(move || for i in get_tty().unwrap().bytes() {
| ^^^^^^^ not found in this scope

error[E0425]: cannot find function `set_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:45:9
|
45 | set_terminal_attr(&self.prev_ios).unwrap();
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `get_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:90:23
|
90 | let mut ios = get_terminal_attr()?;
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `raw_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:93:9
|
93 | raw_terminal_attr(&mut ios);
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `set_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:95:9
|
95 | set_terminal_attr(&ios)?;
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `set_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:107:9
|
107 | set_terminal_attr(&self.prev_ios)?;
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `get_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:113:23
|
113 | let mut ios = get_terminal_attr()?;
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `raw_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:114:9
|
114 | raw_terminal_attr(&mut ios);
| ^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `set_terminal_attr` in this scope
--> C:\Users\John\.cargo\registry\src\github.com-1ecc6299db9ec823\termion-1.5.5\src\raw.rs:115:9
|
115 | set_terminal_attr(&ios)?;
| ^^^^^^^^^^^^^^^^^ not found in this scope

error: aborting due to 15 previous errors

Some errors have detailed explanations: E0425, E0432, E0433.
For more information about an error, try `rustc --explain E0425`.
error: could not compile `termion`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: failed to compile `logtail v0.1.2`, intermediate artifacts can be found at `C:\Users\John\AppData\Local\Temp\cargo-install2u6Wab`

Caused by:
build failed
```