[REF] component: rename t-keep-alive to t-keepalive

This is useful to preserve the following nice property: when we have an
attribute t-something-someotherthing, we can get the directive name by
removing 't-' at the front, and splitting on '-'.

examples/web/static/src/xml/templates.xml

@@ -3,7 +3,7 @@
 
   <div t-name="web.web_client" class="o_web_client">
     <t t-widget="Navbar" t-props="{inHome:state.inHome,app:state.currentApp}" />
-    <t t-widget="HomeMenu" t-if="state.inHome" t-keep-alive="1" t-props="{menuInfo:props.menuInfo}" />
+    <t t-widget="HomeMenu" t-if="state.inHome" t-keepalive="1" t-props="{menuInfo:props.menuInfo}" />
     <div class="o_content" t-att-class="state.inHome ? 'o_hidden' : ''" t-ref="'content'"/>
     <div class="o_notification_container">
       <t t-foreach="state.notifications" t-as="notif">

src/qweb.ts

@@ -195,7 +195,7 @@ export class QWeb {
       attf: 1,
       props: 1,
       key: 1,
-      keep: 1 // todo: rename keep-alive to keepalive
+      keepalive: 1
     };
     [
       forEachDirective,
@@ -940,7 +940,7 @@ const widgetDirective: Directive = {
     ctx.addLine("//WIDGET");
     ctx.rootContext.shouldDefineOwner = true;
     let props = node.getAttribute("t-props");
-    let keepAlive = node.getAttribute("t-keep-alive") ? true : false;
+    let keepAlive = node.getAttribute("t-keepalive") ? true : false;
 
     // t-on- events...
     const events: [string, string][] = [];

tests/component.test.ts

@@ -739,10 +739,10 @@ describe("composition", () => {
     );
   });
 
-  test("sub widgets with t-keep-alive are not destroyed if no longer in dom", async () => {
+  test("sub widgets with t-keepalive are not destroyed if no longer in dom", async () => {
     class ParentWidget extends Widget {
       state = { ok: true };
-      inlineTemplate = `<div><t t-if="state.ok"><t t-widget="counter" t-keep-alive="1"/></t></div>`;
+      inlineTemplate = `<div><t t-if="state.ok"><t t-widget="counter" t-keepalive="1"/></t></div>`;
       widgets = { counter: Counter };
     }
     const widget = new ParentWidget(env);
@@ -765,10 +765,10 @@ describe("composition", () => {
     );
   });
 
-  test("sub widgets dom state with t-keep-alive is preserved", async () => {
+  test("sub widgets dom state with t-keepalive is preserved", async () => {
     class ParentWidget extends Widget {
       state = { ok: true };
-      inlineTemplate = `<div><t t-if="state.ok"><t t-widget="InputWidget" t-keep-alive="1"/></t></div>`;
+      inlineTemplate = `<div><t t-if="state.ok"><t t-widget="InputWidget" t-keepalive="1"/></t></div>`;
       widgets = { InputWidget };
     }
     class InputWidget extends Widget {