Merge pull request #1630 from magento-engcom/2.2-develop-prs

#11765 Allows modules with underscores in name to add blocks to layout via XML by @bentideswell
#11745 [Backport 2.2-develop] Fix label to avoid wrapping poorly,now break by word by @enriquei4
#11749 [Backport 2.2-develop] Fix datetime type product that show current date when is empty in grids by @enriquei4

Author: Oleksii Korshenko

app/code/Magento/Ui/view/base/web/js/grid/columns/date.js

@@ -39,7 +39,7 @@ define([
         getLabel: function (value, format) {
             var date = moment(this._super());
 
-            date = date.isValid() ?
+            date = date.isValid() && value[this.index] ?
                 date.format(format || this.dateFormat) :
                 '';
 

app/design/adminhtml/Magento/backend/web/css/styles-old.less

@@ -1383,7 +1383,6 @@
             line-height: 1.33;
             vertical-align: middle;
             white-space: normal;
-            word-break: break-all;
 
             &[data-config-scope] {
                 position: relative;

lib/internal/Magento/Framework/View/Layout/etc/elements.xsd

@@ -138,7 +138,7 @@
 
     <xs:simpleType name="blockClassType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[A-Z][a-zA-Z\d]*(\\[A-Z][a-zA-Z\d]*)*"/>
+            <xs:pattern value="[A-Z][_a-zA-Z\d]*(\\[A-Z][_a-zA-Z\d]*)*"/>
         </xs:restriction>
     </xs:simpleType>