feat(inputters): Support front/main/back matter divisions in master d…

…ocuments

examples/manual-masterdoc/bookdivisions.dj

@@ -0,0 +1,84 @@
+# Book divisions
+
+In §[](#masterdoc-content-basic), we explored how to declare a simple book consisting of chapters or parts.
+For books with chapters only:
+
+
+```yaml
+content:
+  chapters:
+    ⟨...⟩
+```
+
+Or for books with parts:
+
+```yaml
+content:
+  parts:
+    ⟨...⟩
+```
+
+Actually, this is equivalent to the following full syntax:
+
+```yaml
+content:
+  mainmatter:
+    ⟨parts or chapters⟩
+```
+
+That is, your content is assumed to be part of the main matter by default.
+Some books, however, require a more complex structure, dividing content into front matter, main matter, and back matter.
+This is particularly common in academic works, where the front matter might include a preface, dedication, and table of contents.
+
+## Front, main and back divisions
+
+Each division begins on an odd-numbered page.
+Divisions influence both the format and numbering of pages:
+
+ - The front matter uses roman numerals for page numbers by default.
+ - The main and back matter use arabic numerals for page numbers by default.
+
+These defaults can be overridden to suit specific requirements, with adequate styles.
+Page numbering resets whenever the format changes between divisions (e.g., front matter from i--viii, main matter from 1--148).
+
+Divisions also influence the numbering of parts and chapters:
+
+ - In the front matter and back matter, parts and chapters are unnumbered by definition.
+ - In the main matter, parts and chapters are numbered by default, though this behavior can be customized with styles.
+
+All default styles can be overridden to suit specific requirements, but we will cover this in a later section.
+All divisions can include parts.
+However, it is up to you to maintain consistency with your structural expectations.
+
+```yaml
+content:
+  frontmatter:
+    ⟨parts or chapters⟩
+  mainmatter:
+    ⟨parts or chapters⟩
+  backmatter:
+    ⟨parts or chapters⟩
+```
+
+Below is an example of how to declare a book that incorporates these divisions.
+
+```yaml
+content:
+  frontmatter:
+    chapters:
+      - preface.dj
+      - dedication.dj
+  mainmatter:
+    parts:
+      - caption: Part 1
+        content:
+          - chapt1-1.dj
+          - chapt1-2.dj
+      - caption: Part 2
+        content:
+          - chapt2-1.dj
+          - chapt2-2.dj
+  backmatter:
+    chapters:
+      - postface.dj
+```

examples/manual-masterdoc/masterdoc.dj

@@ -55,11 +55,11 @@ sile:
     textsubsuper.fake: false
     typesetter.italicCorrection: true
   packages:
-    - dropcaps
-    - couyards
-chapters:
-  - chap1.dj
-  - chap2.dj
+    - resilient.poetry
+content:
+  chapters:
+    - chap1.dj
+    - chap2.dj
 ```
 
 The `masterfile` entry is a number corresponding to a version, for compatibility purposes.[^masterdoc-compat]
@@ -104,6 +104,7 @@ The `sile` object provides intructions for processing the master document with S
 - The `packages` object lists extra packages that SILE must use.
   It can be used to load add-on packages needed by your content but not already provided by the document class and its supporting packages.
 
+{#masterdoc-content-basic}
 ## Up to the content
 
 Last but not least, the `chapters` array (or `parts`, see further below) lists the files to include in the work.

examples/sile-resilient-manual.silm

@@ -53,6 +53,7 @@ parts:
     content:
       - manual-masterdoc/masterdoc.dj
       - manual-masterdoc/bookmatters.dj
+      - manual-masterdoc/bookdivisions.dj
       - manual-masterdoc/bibliographies.dj
   - file: manual-parts/part-layouts.dj
     content: