(build) Add GRM template files

These files are used to control the exact format of the release notes
that are generated when using GitReleaseManager.

.templates/default/create/footer.sbn

@@ -0,0 +1,10 @@
+{{ if config.create.include_footer }}
+
+### {{ config.create.footer_heading }}
+
+{{  if config.create.milestone_replace_text
+        replace_milestone_title config.create.footer_content config.create.milestone_replace_text milestone.target.title
+    else
+        config.create.footer_content
+    end
+end }}

.templates/default/index.sbn

@@ -0,0 +1,10 @@
+{{-
+    include 'release-info'
+    if milestone.target.description
+        include 'milestone'
+    end
+    include 'issues' | string.rstrip
+    if template_kind == "CREATE"
+        include 'create/footer'
+    end
+~}}

.templates/default/issue-details.sbn

@@ -0,0 +1,5 @@
+### {{ issue_label }}
+
+{{ for issue in issues.items[issue_label]
+    include 'issue-note'
+end }}

.templates/default/issue-note.sbn

@@ -0,0 +1 @@
+- {{ issue.title }} - see [#{{ issue.number }}]({{ issue.html_url }})

.templates/default/issues.sbn

@@ -0,0 +1,4 @@
+
+{{ for issue_label in issue_labels
+    include 'issue-details'
+end }}

.templates/default/milestone.sbn

@@ -0,0 +1,2 @@
+
+{{ milestone.target.description }}

.templates/default/release-info.sbn

@@ -0,0 +1,10 @@
+{{
+    if issues.count > 0
+        if commits.count > 0
+}}As part of this release we had [{{ commits.count }} {{ commits.count | string.pluralize "commit" "commits" }}]({{ commits.html_url }}) which resulted in [{{ issues.count }} {{ issues.count | string.pluralize "issue" "issues" }}]({{ milestone.target.html_url }}?closed=1) being closed.
+{{      else
+}}As part of this release we had [{{ issues.count }} {{ issues.count | string.pluralize "issue" "issues" }}]({{ milestone.target.html_url }}?closed=1) closed.
+{{      end
+    else if commits.count > 0
+}}As part of this release we had [{{ commits.count }} {{ commits.count | string.pluralize "commit" "commits" }}]({{ commits.html_url }}).
+{{  end -}}