Support legacy PHP 5.3 through PHP 7.2 and HHVM

.travis.yml

@@ -1,14 +1,26 @@
 language: php
 
-sudo: false
-
 php:
-  - 5.3
+# - 5.3 # requires old distro, see below
   - 5.4
   - 5.5
   - 5.6
-  - 7
-  - hhvm
+  - 7.0
+  - 7.1
+  - 7.2
+  - hhvm # ignore errors, see below
+
+# lock distro so future defaults will not break the build
+dist: trusty
+
+matrix:
+  include:
+    - php: 5.3
+      dist: precise
+  allow_failures:
+    - php: hhvm
+
+sudo: false
 
 install:
   - composer install --prefer-source --no-interaction

README.md

@@ -72,6 +72,11 @@ $ php graph-composer.phar export ~/path/to/your/project
 
 You can grab a copy of clue/graph-composer in either of the following ways.
 
+This project aims to run on any platform and thus does not require any PHP
+extensions and supports running on legacy PHP 5.3 through current PHP 7+ and
+HHVM.
+It's *highly recommended to use PHP 7+* for this project.
+
 ### As a phar (recommended)
 
 You can simply download a pre-compiled and ready-to-use version as a Phar