Add information about required and suggested extensions to composer.json

Fixes #12785

Signed-off-by: Michal Čihař <michal@cihar.com>

ChangeLog

@@ -14,6 +14,7 @@ phpMyAdmin - ChangeLog
 - issue #12780 Format button replaces all text with blank spaces
 - issue #12786 Fixed database searching
 - issue #12792 Fixed javascript error on new version link
+- issue #12785 Add information about required and suggested extensions to composer.json
 
 4.6.5.2 (2016-12-05)
 - issue #12765 Fixed SQL export with newlines

composer.json

@@ -21,7 +21,19 @@
     },
     "non-feature-branches": ["RELEASE_.*"],
     "require": {
-        "php": ">=5.5.0"
+        "php": ">=5.5.0",
+        "ext-mbstring": "*",
+        "ext-mysqli": "*",
+        "ext-xml": "*",
+        "ext-json": "*"
+    },
+    "suggest": {
+        "ext-curl": "Updates checking",
+        "ext-opcache": "Better performance",
+        "ext-zlib": "For gz import and export",
+        "ext-bz2": "For bzip2 import and export",
+        "ext-zip": "For zip import and export",
+        "ext-gd2": "For image transformations"
     },
     "require-dev": {
         "satooshi/php-coveralls": "~0.6",