Add Travis config for various checks

This adds continuous-integration configuration for checking PHP
lint, coding standards, and non-executable files.

Refs: #817

.gitignore

@@ -16,4 +16,8 @@
 
 # Eclipse
 .settings
-.project
+.project
+
+# Composer
+vendor/
+

.phpcs.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+<ruleset>
+
+    <rule ref="Generic.Arrays.ArrayIndent">
+        <properties>
+            <property name="indent" value="2" />
+        </properties>
+    </rule>
+    <rule ref="Generic.WhiteSpace.ScopeIndent">
+        <properties>
+            <property name="indent" value="2" />
+        </properties>
+    </rule>
+    <rule ref="Generic.Functions.OpeningFunctionBraceBsdAllman" />
+    <rule ref="Squiz.Strings.ConcatenationSpacing" />
+
+    <file>.</file>
+
+    <exclude-pattern>./vendor</exclude-pattern>
+
+</ruleset>

.travis.yml

@@ -0,0 +1,16 @@
+language: php
+
+php:
+  - '5.6'
+  - '7.0'
+  - '7.1'
+  - '7.2'
+
+install:
+  - composer install
+
+script:
+  - composer validate
+  - vendor/bin/parallel-lint . --exclude vendor/
+  - vendor/bin/phpcs -p -s
+  - vendor/bin/minus-x check .

composer.json

@@ -0,0 +1,15 @@
+{
+  "name": "piwigo/piwigo",
+  "description": "A full featured open source photo gallery for the web.",
+  "license": "GPL-2.0-only",
+  "require-dev": {
+    "jakub-onderka/php-parallel-lint": "^1.0",
+    "squizlabs/php_codesniffer": "^3.0",
+    "mediawiki/minus-x": "^0.3"
+  },
+  "config": {
+    "platform": {
+      "php": "5.6"
+    }
+  }
+}