Build system: Don't use Composer for dev dependencies

PHP_CodeSniffer and phpDocumentor are external tools which should never affect Pico's environment, thus we rather use PHARs in the future.

.build/install.sh

@@ -9,11 +9,31 @@ case "$1" in
         echo "Synchronizing package index files..."
         sudo apt-get update
 
-        echo "Installing packages..."
+        echo "Installing cloc..."
         sudo apt-get install -y cloc
+
+        echo "Installing phpDocumentor..."
+        curl --location --output "$PICO_TOOLS_DIR/phpdoc" \
+            "https://github.com/phpDocumentor/phpDocumentor2/releases/latest/download/phpDocumentor.phar"
+        chmod +x "$PICO_TOOLS_DIR/phpdoc"
         ;;
 esac
 
+echo "Installing PHP_CodeSniffer..."
+if [ "$(php -r 'echo PHP_VERSION_ID;')" -ge 50400 ]; then
+    PHPCS_DOWNLOAD="https://github.com/squizlabs/PHP_CodeSniffer/releases/latest/download/"
+else
+    PHPCS_DOWNLOAD="https://github.com/squizlabs/PHP_CodeSniffer/releases/download/2.9.2/"
+fi
+
+curl --location --output "$PICO_TOOLS_DIR/phpcs" \
+    "$PHPCS_DOWNLOAD/phpcs.phar"
+chmod +x "$PICO_TOOLS_DIR/phpcs"
+
+curl --location --output "$PICO_TOOLS_DIR/phpcbf" \
+    "$PHPCS_DOWNLOAD/phpcbf.phar"
+chmod +x "$PICO_TOOLS_DIR/phpcbf"
+
 echo
 
 # setup composer

composer.json

@@ -38,10 +38,6 @@
         "picocms/pico-deprecated": "PicoDeprecated's purpose is to maintain backward compatibility to older versions of Pico.",
         "picocms/composer-installer": "This Composer plugin is responsible for installing Pico plugins and themes using the Composer package manager."
     },
-    "require-dev" : {
-        "phpdocumentor/phpdocumentor": "^2.9",
-        "squizlabs/php_codesniffer": "^2.9"
-    },
     "autoload": {
         "psr-0": {
             "Pico": "lib/",