fix paragraph object issues

add object validation script (src\classes\Snippets.class.php)
change object array value to string and content variable to text in
(src\data\uri\default\index.json)
change object array value to string and content variable to text in
(src\data\uri\user\index.json)
make object editable in snippet
(src\templates'snippets\typography\paragraph\edit.tpl)
change object array import to string import
(src\templates'snippets\typography\paragraph\index.tpl)
fix heading object issues

add nl2br php function to variable