feat(item-group): add the item group component and move styles

- styles are moved out of item into item group for it
- updated to work like v3 styles

packages/core/src/components/item-group/item-group.ios.scss

@@ -0,0 +1,15 @@
+@import "./item-group";
+@import "./item-group.ios.vars";
+
+
+// iOS Item Group
+// --------------------------------------------------
+
+.item-group-ios ion-item:first-child .item-inner {
+  border-top-width: 0;
+}
+
+.item-group-ios ion-item:last-child .item-inner,
+.item-group-ios .item-wrapper:last-child .item .item-inner {
+  border: 0;
+}

packages/core/src/components/item-group/item-group.ios.vars.scss

@@ -0,0 +1,4 @@
+@import "../../themes/ionic.globals.ios";
+
+// iOS Item Group
+// --------------------------------------------------

packages/core/src/components/item-group/item-group.md.scss

@@ -0,0 +1,15 @@
+@import "./item-group";
+@import "./item-group.md.vars";
+
+
+// Material Design Item Group
+// --------------------------------------------------
+
+.item-group-md ion-item:first-child .item-inner {
+  border-top-width: 0;
+}
+
+.item-group-md ion-item:last-child .item-inner,
+.item-group-md .item-wrapper:last-child .item .item-inner {
+  border: 0;
+}

packages/core/src/components/item-group/item-group.md.vars.scss

@@ -0,0 +1,4 @@
+@import "../../themes/ionic.globals.md";
+
+// Material Design Item Group
+// --------------------------------------------------

packages/core/src/components/item-group/item-group.scss

@@ -0,0 +1,9 @@
+@import "./item-group.vars";
+
+
+// Item Group
+// --------------------------------------------------
+
+ion-item-group {
+  display: block;
+}

packages/core/src/components/item-group/item-group.tsx

@@ -0,0 +1,18 @@
+import { Component } from '@stencil/core';
+
+
+@Component({
+  tag: 'ion-item-group',
+  styleUrls: {
+    ios: 'item-group.ios.scss',
+    md: 'item-group.md.scss'
+  },
+  host: {
+    theme: 'item-group'
+  }
+})
+export class ItemGroup {
+  render() {
+    return <slot></slot>;
+  }
+}

packages/core/src/components/item-group/item-group.vars.scss

@@ -0,0 +1,5 @@
+@import "../../themes/ionic.globals";
+
+
+// Item Group
+// --------------------------------------------------

packages/core/src/components/item/item.ios.scss

@@ -167,19 +167,6 @@
 }
 
 
-// iOS Item Group
-// --------------------------------------------------
-
-ion-item-group .item-ios:first-child .item-inner {
-  border-top-width: 0;
-}
-
-ion-item-group .item-ios:last-child .item-inner,
-ion-item-group .item-wrapper:last-child .item-ios .item-inner {
-  border: 0;
-}
-
-
 // Generate iOS Item and Item Divider Colors
 // --------------------------------------------------
 

packages/core/src/components/item/item.md.scss

@@ -153,19 +153,6 @@
 }
 
 
-// Material Design Item Group
-// --------------------------------------------------
-
-ion-item-group .item-md:first-child .item-inner {
-  border-top-width: 0;
-}
-
-ion-item-group .item-md:last-child .item-inner,
-ion-item-group .item-md .item-wrapper:last-child .item-inner {
-  border: 0;
-}
-
-
 // Generate Material Design Item and Item Divider Colors
 // --------------------------------------------------