Adding support for stdin input in the encode64 plugin

plugins/encode64/encode64.plugin.zsh

@@ -1,4 +1,17 @@
-encode64(){ echo -n $1 | base64 }
-decode64(){ echo -n $1 | base64 --decode }
+encode64(){ 
+    if [ $# -eq 0 ]; then
+        cat | base64
+    else
+        echo -n "$*" | base64
+    fi
+}
+
+decode64(){ 
+    if [ $# -eq 0 ]; then
+        cat | base64 --decode
+    else
+        echo -n "$*" | base64 --decode
+    fi
+}
 alias e64=encode64
 alias d64=decode64