Refactor: Rewrote the help text database (dd_help)

dd_help.c was rewritten to use C++, libdeng2, and more efficient
data structures. It now also supports full Unicode text.

Updated the module's internal C API with modern conventions in mind
(the API itself was left unchanged).

Important note: the source data (cphelp.txt, conhelp.txt) is now read
directly from within the PK3s using libdeng2. Thus it is no longer
necessary to deploy them as "startupdata" in the installation.

doomsday/engine/engine.pro

@@ -457,7 +457,7 @@ SOURCES += \
     src/con_data.cpp \
     src/con_main.c \
     src/dd_games.cpp \
-    src/dd_help.c \
+    src/dd_help.cpp \
     src/dd_init.cpp \
     src/dd_loop.c \
     src/dd_main.cpp \
@@ -658,9 +658,6 @@ mod.files = \
     $$DENG_MODULES_DIR/Config.de \
     $$DENG_MODULES_DIR/recutil.de
 
-startupdata.files = \
-    data/cphelp.txt
-
 # These fonts may be needed during the initial startup busy mode.
 startupfonts.files = \
     data/fonts/console11.dfn \
@@ -690,11 +687,10 @@ macx {
 
     data.path         = $${res.path}
     mod.path          = $${res.path}/modules
-    startupdata.path  = $${res.path}/data
     startupfonts.path = $${res.path}/data/fonts
     startupgfx.path   = $${res.path}/data/graphics
 
-    QMAKE_BUNDLE_DATA += mod res data startupfonts startupdata startupgfx
+    QMAKE_BUNDLE_DATA += mod res data startupfonts startupgfx
 
     QMAKE_INFO_PLIST = ../build/mac/Info.plist
 
@@ -732,11 +728,10 @@ macx {
 
 !macx {
     # Common (non-Mac) parts of the installation.
-    INSTALLS += target data startupdata startupgfx startupfonts mod
+    INSTALLS += target data startupgfx startupfonts mod
 
     target.path       = $$DENG_BIN_DIR
     data.path         = $$DENG_DATA_DIR
-    startupdata.path  = $$DENG_DATA_DIR
     startupgfx.path   = $$DENG_DATA_DIR/graphics
     startupfonts.path = $$DENG_DATA_DIR/fonts
     mod.path          = $$DENG_BASE_DIR/modules

doomsday/engine/include/dd_help.h

@@ -33,6 +33,8 @@
 extern "C" {
 #endif
 
+typedef void const *HelpNode;
+
 // Help string types.
 enum {
     HST_DESCRIPTION,
@@ -44,12 +46,45 @@ enum {
 
 void DH_Register(void);
 
+/**
+ * Initializes the help string database. After which, attempts to read the
+ * engine's own help string file.
+ */
 void DD_InitHelp(void);
+
+/**
+ * Attempts to read help strings from the game-specific help file.
+ */
 void DD_ReadGameHelp(void);
+
+/**
+ * Shuts down the help string database. Frees all storage and destroys
+ * database itself.
+ */
 void DD_ShutdownHelp(void);
 
-void* DH_Find(const char* id);
-char* DH_GetString(void* found, int type);
+/**
+ * Finds a node matching the ID. Use DH_GetString to read strings from it.
+ *
+ * @param id  Help node ID to be searched for.
+ *
+ * @return Pointer to help data, if matched; otherwise @c NULL.
+ */
+HelpNode DH_Find(char const *id);
+
+/**
+ * Return a string from within the helpnode. Strings are stored internally
+ * and indexed by their type (e.g. HST_DESCRIPTION).
+ *
+ * @param foundNode  The helpnode to return the string from.
+ * @param type       The string type (index) to look for within the node.
+ *
+ * @return Pointer to the found string; otherwise @c NULL. Note, may also
+ * return @c NULL, if passed an invalid helpnode ptr OR the help string
+ * database has not beeen initialized yet. The returned string is actually from
+ * an AutoStr; it will only be valid until the next garbage recycling.
+ */
+char const *DH_GetString(HelpNode found, int type);
 
 #ifdef __cplusplus
 } // extern "C"

doomsday/engine/src/con_data.cpp

@@ -1150,7 +1150,7 @@ void Con_PrintCCmdUsage(ccmd_t* ccmd, boolean printInfo)
     if(printInfo)
     {
         // Check for extra info about this ccmd's usage.
-        char* info = DH_GetString(DH_Find(ccmd->name), HST_INFO);
+        char const *info = DH_GetString(DH_Find(ccmd->name), HST_INFO);
         if(info)
         {
             // Lets indent for neatness.
@@ -1487,9 +1487,9 @@ static void printHelpAbout(char const* query)
     // Try the console commands first.
     if(ccmd_t* ccmd = Con_FindCommand(query))
     {
-        void* helpRecord = DH_Find(ccmd->name);
-        char const* description = DH_GetString(helpRecord, HST_DESCRIPTION);
-        char const* info = DH_GetString(helpRecord, HST_INFO);
+        HelpNode help = DH_Find(ccmd->name);
+        char const* description = DH_GetString(help, HST_DESCRIPTION);
+        char const* info = DH_GetString(help, HST_INFO);
 
         if(description)
             Con_Printf("%s\n", description);
@@ -1588,8 +1588,8 @@ static int printKnownWordWorker(knownword_t const* word, void* parameters)
     switch(word->type)
     {
     case WT_CCMD: {
-        ccmd_t* ccmd = (ccmd_t*) word->data;
-        char* str;
+        ccmd_t *ccmd = (ccmd_t *) word->data;
+        char const *str;
 
         if(ccmd->prevOverload)
             return 0; // Skip overloaded variants.