help: Skip images in the source file

Allow images in the source markdown files, but skip them on calculator

Note that we need to skip them at runtime if we want to be able to
have them in the GitHub file correctly.

Fixes: #438

Signed-off-by: Christophe de Dinechin <christophe@dinechin.org>

Makefile

@@ -90,13 +90,15 @@ sim:	sim/gcc111libbid.a	\
 clangdb: sim/$(TARGET).mak .ALWAYS
 	cd sim && rm -f *.o && compiledb make -f $(TARGET).mak && mv compile_commands.json ..
 
-keyboard: sim/keyboard-db48x.png Keyboard-Layout.png Keyboard-Cutout.png
+keyboard: Keyboard-Layout.png Keyboard-Cutout.png sim/keyboard-db48x.png help/keyboard.png doc/keyboard.png
 Keyboard-Layout.png: DB48X-Keys/DB48X-Keys.001.png
 	cp $< $@
 Keyboard-Cutout.png: DB48X-Keys/DB48X-Keys.002.png
 	cp $< $@
 sim/keyboard-db48x.png: DB48X-Keys/DB48X-Keys.001.png
 	convert $< -crop 698x878+151+138 $@
+%/keyboard.png: sim/keyboard-db48x.png
+	cp $< $@
 
 QMAKE_debug=debug
 QMAKE_release=release

doc/0-Overview.md

@@ -118,6 +118,8 @@ gives a variety of special characters.
 
 ### Key mapping
 
+![DB48X keyboard layout](keyboard.png)
+
 Some keys that have little use or no direct equivalent for RPL are remapped
 as follows:
 

help/db48x.md

@@ -118,6 +118,8 @@ gives a variety of special characters.
 
 ### Key mapping
 
+![db48x keyboard layout](keyboard.png)
+
 Some keys that have little use or no direct equivalent for RPL are remapped
 as follows:
 

help/db50x.md

@@ -83,7 +83,7 @@ characters are labeled on the right of each key on the DM42's keyboard.
 
 When *Alpha* mode is active, an _ABC_ indicator shows up in the annunciator area
 at the top of the screen. For lowercase entry, the indicator changes to
-_abc_. In the rest of this document, Alpha mode will be indicated as 🔤.
+_abc_.
 
 There are three ways to enter *Alpha* mode:
 
@@ -118,6 +118,8 @@ gives a variety of special characters.
 
 ### Key mapping
 
+![db50x keyboard layout](keyboard.png)
+
 Some keys that have little use or no direct equivalent for RPL are remapped
 as follows:
 

src/user_interface.cc

@@ -2411,6 +2411,17 @@ bool user_interface::draw_help()
                 }
                 break;
 
+            case '!':
+                // Skip images
+                if (last == '\n')
+                {
+                    unicode c = helpfile.get();
+                    while (c != '\n' && c != unicode(EOF))
+                        c = helpfile.get();
+                }
+                skip = true;
+                break;
+
             case '*':
                 if (last == '\n' && helpfile.peek() == ' ')
                 {