Add pear modules, mail and net_smtp via composer (#93)

Add pear modules, mail and net_smtp via composer, remove php 5.6 build due to phpunit 6

lib/composer/vendor/phpdocumentor/reflection-docblock/easy-coding-standard.neon

@@ -0,0 +1,31 @@
+includes:
+    - temp/ecs/config/clean-code.neon
+    - temp/ecs/config/psr2-checkers.neon
+    - temp/ecs/config/spaces.neon
+    - temp/ecs/config/common.neon
+
+checkers:
+    PhpCsFixer\Fixer\Operator\ConcatSpaceFixer:
+        spacing: one
+
+parameters:
+    exclude_checkers:
+        # from temp/ecs/config/common.neon
+        - PhpCsFixer\Fixer\ClassNotation\OrderedClassElementsFixer
+        - PhpCsFixer\Fixer\PhpUnit\PhpUnitStrictFixer
+        - PhpCsFixer\Fixer\ControlStructure\YodaStyleFixer
+        # from temp/ecs/config/spaces.neon
+        - PhpCsFixer\Fixer\Operator\NotOperatorWithSuccessorSpaceFixer
+
+    skip:
+        SlevomatCodingStandard\Sniffs\Classes\UnusedPrivateElementsSniff:
+            # WIP code
+            - src/DocBlock/StandardTagFactory.php
+        PHP_CodeSniffer\Standards\Generic\Sniffs\CodeAnalysis\EmptyStatementSniff:
+            # WIP code
+            - src/DocBlock/StandardTagFactory.php
+        PHP_CodeSniffer\Standards\Squiz\Sniffs\Classes\ValidClassNameSniff:
+            - src/DocBlock/Tags/Return_.php
+            - src/DocBlock/Tags/Var_.php
+        PHP_CodeSniffer\Standards\Generic\Sniffs\NamingConventions\CamelCapsFunctionNameSniff:
+            - */tests/**