init: initial repo contents with example fleshing out API

Signed-off-by: Paul Osborne <osbpau@gmail.com>

Author: posborne

.gitignore

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+\#*\#
+.\#*
+target
+Cargo.lock

Cargo.toml

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+[package]
+name = "sysfs-pwm"
+version = "0.1.0"
+authors = ["Paul Osborne <osbpau@gmail.com>"]
+license = "MIT/Apache-2.0"
+homepage = "https://github.com/posborne/rust-sysfs-pwm"
+documentation = "https://posborne.github.io/rust-sysfs-pwm"
+description = """
+Provides access to the Linux sysfs interfaces to PWMs.
+Via this crate you can export, unexport, and control PWM pins for
+which there is an appropriate driver loaded in the kernel.
+
+See https://www.kernel.org/doc/Documentation/pwm.txt
+"""
+
+[dependencies]

README.md

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+rust-sysfs-pwm
+==============
+
+[![Build Status](https://travis-ci.org/posborne/rust-sysfs-pwm.svg?branch=master)](https://travis-ci.org/posborne/rust-sysfs-pwm)
+[![Version](https://img.shields.io/crates/v/sysfs-pwm.svg)](https://crates.io/crates/sysfs-pwm)
+[![License](https://img.shields.io/crates/l/sysfs-pwm.svg)](https://github.com/posborne/rust-sysfs-pwm/blob/master/README.md#license)
+
+- [API Documentation](http://posborne.github.io/rust-sysfs-pwm/)
+
+rust-sysfs-pwm is a rust library/crate providing access to the [Linux
+sysfs PWM interface](https://www.kernel.org/doc/Documentation/pwm.txt).
+It seeks to provide an API that is safe, convenient, and efficient.
+
+Install/Use
+-----------
+
+To use `sysfs-pwm`, first add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+# or latest version
+sysfs-pwm = "^0.1.0"
+```
+
+Then, add this to your crate root:
+
+```rust
+extern crate sysfs_pwm;
+```
+
+Example/API
+-----------
+
+Controlling a PWM (this example works on the Rasbperry Pi):
+
+```rust
+extern crate sysfs_pwm;
+use sysfs_pwm::{PWM};
+
+const RPI_PWM_CHIP: u32 = 1;
+
+fn pwm_increase_to_max(pwm: &PWM,
+                       duration_ms: u32,
+                       update_period: u32) {
+    let mut step: f32 = duration_ms / update_period;
+    let duty_cycle: f32 = 0.0;
+    while duty_cycle < 1.0 {
+        pwm.set_duty_cycle(duty_cycle);
+        duty_cycle += step;
+    }
+    pwm.set_duty_cycle(1.0);
+}
+
+fn pwm_decrease_to_minimum(pwm: &PWM,
+                           duration_ms: u32,
+                           update_period: u32) {
+    let mut step: f32 = duration_ms / update_period;
+    let mut duty_cycle = 1.0;
+    while duty_cycle > 0.0 {
+        pwm.set_duty_cycle(duty_cycle);
+        duty_cycle -= step;
+    }
+    pwm.set_duty_cycle(0.0)
+}
+
+/// Make an LED "breathe" by increasing and
+/// decreasing the brightness
+fn main() {
+    let my_pwm = PWM::new(1, 127); // number depends on chip, etc.
+    my_pwm.with_exported(|| {
+        loop {
+            pwm_increase_to_max(pwm, 1000, 20);
+            pwm_decrease_to_minimum(pwm, 1000, 20);
+        }
+    }).unwrap();
+}
+```
+
+Features
+--------
+
+...
+
+Cross Compiling
+---------------
+
+Most likely, the machine you are running on is not your development
+machine (although it could be).  In those cases, you will need to
+cross-compile.  The [instructions here][rust-cross] provide great details on cross
+compiling for your platform.
+
+[rust-cross]: https://github.com/japaric/rust-cross
+
+Running the Example
+-------------------
+
+Cross-compiling can be done by specifying an appropriate target.  You
+can then move that to your device by whatever means and run it.
+
+```
+$ cargo build --target=arm-unknown-linux-gnueabihf --example breathe
+$ scp target/arm-unknown-linux-gnueabihf/debug/examples/breathe ...
+```
+
+License
+-------
+
+```
+Copyright (c) 2016, Paul Osborne <ospbau@gmail.com>
+
+Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+http://www.apache.org/license/LICENSE-2.0> or the MIT license
+<LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+option.  This file may not be copied, modified, or distributed
+except according to those terms.
+```

src/lib.rs

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+#[test]
+fn it_works() {
+}