Remove examples and other files from exports

Examples require 'require-dev' dependencies, which aren't available if the package is installed via Composer as a dependency.

Closes #268.

.gitattributes

@@ -1,9 +1,13 @@
-/test               export-ignore
-/.coveralls.yml     export-ignore
-/.gitattributes     export-ignore
-/.gitignore         export-ignore
-/.php_cs            export-ignore
-/.travis.yml        export-ignore
-/phpunit.xml        export-ignore
-*                   text           eol=lf
-*.png               -text
+/examples            export-ignore
+/test                export-ignore
+/.editorconfig       export-ignore
+/.gitattributes      export-ignore
+/.gitignore          export-ignore
+/.gitmodules         export-ignore
+/.php_cs.dist        export-ignore
+/.phpstorm.meta.php  export-ignore
+/.travis.yml         export-ignore
+/infection.json.dist export-ignore
+/phpunit.xml.dist    export-ignore
+*                    text           eol=lf
+*.png                -text