Add README.

Author: bertptrs

.travis.yml

@@ -8,4 +8,5 @@ php:
 install:
     - composer install
 
-script: phpunit
+script:
+    - vendor/bin/grumphp run

README.md

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+# PHPStreams
+
+[![Latest Stable Version](https://poser.pugx.org/bertptrs/phpstreams/v/stable)](https://packagist.org/packages/bertptrs/phpstreams) [![Total Downloads](https://poser.pugx.org/bertptrs/phpstreams/downloads)](https://packagist.org/packages/bertptrs/phpstreams) [![License](https://poser.pugx.org/bertptrs/phpstreams/license)](https://packagist.org/packages/bertptrs/phpstreams) [![Build Status](https://travis-ci.org/bertptrs/phpstreams.svg?branch=master)](https://travis-ci.org/bertptrs/phpstreams)
+
+A partial implementation of the Java 8 Streams API in PHP. PHPStreams
+can use your generators, your arrays and really anything that is
+[Iterable](https://wiki.php.net/rfc/iterable) and convert modify it like
+you're used to using Java Streams!
+
+Using streams and generators, you can easily sort through large amounts
+of data without having to have it all in memory or in scope. Streams
+also make it easier to structure your code, by (more or less) enforcing
+single resposibility.
+
+The library is compatible with PHP 5.5.9 and up.
+
+## Installation
+
+PHPStreams can be installed using Composer. Just run `composer require
+bertptrs/phpstreams` in your project root!
+
+## Usage
+
+Using streams is easy. Say, we want the first 7 odd numbers in the
+Fibonacci sequence. To do this using Streams, we do the following:
+
+```php
+// Define a generator for Fibonacci numbers
+function fibonacci()
+{
+    yield 0;
+    yield 1;
+
+    $prev = 0;
+    $cur = 1;
+
+    while (true) {
+        yield ($new = $cur + $prev);
+        $prev = $cur;
+        $cur = $new;
+    }
+};
+
+// Define a predicate that checks for odd numbers
+$isOdd = function($num) {
+    return $num % 2 == 1;
+};
+
+// Create our stream.
+$stream = new phpstreams\Stream(fibonacci());
+
+// Finally, use these to create our result.
+$oddFibo = $stream->filter($isOdd)  // Keep only the odd numbers
+    ->limit(8)                      // Limit our results
+    ->toArray(false);               // Convert to array, discarding keys
+```
+
+## Documentation
+
+Documentation is mostly done using PHPDoc. I do intend to write actual
+documtation if there is any interest.
+
+## Contributing
+
+I welcome contributions and pull requests. Please note that I do follow
+PSR-2 (and PSR-4 for autoloading). Also, please submit unit tests with
+your work.
+
+GrumPHP enforces at least part of the coding standard, but do make an
+effort to structure your contributions nicely.