Add HTML autoescape (#292)

* add and document set_html_autoescape

* add render_to to Environment that accepts a string (and turns it into a Template)

* code style, update single include

* update ci

* revert macos-14 test

---------

Co-authored-by: pantor <lars.berscheid@online.de>

.github/workflows/ci.yml

@@ -56,18 +56,18 @@ jobs:
             os: windows-2022
             compiler: msvc
 
-          - name: macOS-11-gcc
-            os: macOS-11
+          - name: macOS-12-gcc
+            os: macOS-12
             compiler: gcc
 
-          - name: macOS-11-clang
-            os: macOS-11
-            compiler: clang
-
           - name: macOS-12-clang
             os: macOS-12
             compiler: clang
 
+          # - name: macOS-14-clang
+          #   os: macOS-14
+          #   compiler: clang
+
     steps:
       - uses: actions/checkout@v3