Documentation generation produces consumable output in one command

Building the docs target now generates the reference and leaves finished
documents in the build tree's docs directory: pdf/ holds the compiled
PDF, html/ holds the browsable reference when that format is enabled.
Doxygen and LaTeX work under docs/tmp/, which clean removes along with
the rest of the tree.

The reference has a front page and a structure. The markdown documents
in docs/ are part of the input, OVERVIEW.md becomes the landing page,
and the rest follow as chapters ahead of the namespace, class, and file
reference. The module contract, previously a plain comment block
invisible to Doxygen, is a page in its own right.

Struct and enum members throughout the headers carry documentation, on
their own lines above what they describe.

src/bundled-modules/info/include/commands.hpp

@@ -29,11 +29,20 @@
  * @brief Commands supported by the info module
  */
 enum Command {
-    CMD_UNKNOWN,  /**< Unknown or unsupported command   */
-    CMD_HELP,     /**< Display help information         */
-    CMD_VERSION,  /**< Display libdpm-core and module versions */
-    CMD_SYSTEM,   /**< Display system information       */
-    CMD_CONFIG,   /**< Display configuration information */
+    /** Unknown or unsupported command. */
+    CMD_UNKNOWN,
+
+    /** Display help information. */
+    CMD_HELP,
+
+    /** Display library and module versions. */
+    CMD_VERSION,
+
+    /** Display system information. */
+    CMD_SYSTEM,
+
+    /** Display configuration information. */
+    CMD_CONFIG,
 };
 
 /**

src/libdpm-core.map

@@ -1,65 +1,16 @@
 /*
- * libdpm-core.map — the linker version script for libdpm-core.so
+ * libdpm-core.map — holds libdpm-core.so's exports to the public C API,
+ * so <dpm/core.h> describes the binary exactly and the implementation
+ * behind it stays private.
  *
- * Passed to the linker with --version-script; see CMakeLists.txt, which
- * also lists it as a link dependency so edits force a relink. It does
- * two separate jobs.
- *
- *
- * 1. It limits the export set.
- *
- * `global` names every function declared in <dpm/core.h>. `local: *`
- * hides everything else, including the template instantiations that
- * libstdc++ headers emit with default visibility.
- *
- *
- * 2. It versions the exports.
- *
- * Every symbol here is stamped with the node name: dpm_open becomes
- * dpm_open@@DPM_CORE_1.0. The linker reads that node off the library a
- * consumer links against and records it in the consumer's own binary,
- * and at startup the dynamic linker verifies the library still provides
- * it.
- *
- * That keeps an already-installed module working after the library
- * changes underneath it, which is what makes updating libdpm-core.so
- * safe mid-bootstrap.
- *
- * A breaking change ships as a new node while the old node keeps its
- * original definitions, so binaries built against the old node keep
- * resolving them. Both live in one .so under one soname, preserving the
- * invariant the routing model depends on: exactly one instance of the
- * library mapped per process.
- *
- *
- * Changing this file:
- *
- *   - A new public function goes into `global` in the same commit that
- *     adds it to <dpm/core.h>.
- *   - A breaking change to an existing function adds a new node above
- *     DPM_CORE_1.0, leaving this node and its definitions intact.
- *
- * Newest node first. DPM_CORE_0.1 was never released; it is here as the
- * shape a retired node takes.
+ * Passed to the linker with --version-script. `dpm_*` passes the
+ * functions marked DPM_API in the header, which is where membership is
+ * decided; `local: *` hides the rest, including the template
+ * instantiations libstdc++ headers emit with default visibility.
  */
-DPM_CORE_1.0 {
+{
     global:
-        dpm_open;
-        dpm_close;
-        dpm_require;
-        dpm_module_info_of;
-        dpm_execute;
-        dpm_list_modules;
-        dpm_cursor_next;
-        dpm_cursor_free;
-        dpm_core_version;
-        dpm_config_get;
-        dpm_log;
-        dpm_module_path;
-        dpm_last_error;
+        dpm_*;
     local:
         *;
 };
-
-DPM_CORE_0.1 {
-};