documentation: convert docbook to asciidoc

Many years ago, documentation in fvwm went from raw manpages to docbook
format as a canonical source.  The idea was that this horrific XML
source could generate both manpages and HTML files.

This worked fine, however it meant that writing documentation became an
horrendous chore -- the XML markup was verbose, unsightly and got in the
way of actually documenting anything.

Although markup languages have an overhead, asciidoc seems like a good
replacement for bringing back the documentation to as close to plain
text as possible -- and can still generate the single-source files to
other output formats beyond just man pages.

This commit does a few things:

* Converts roff output to asciidoc (originally via Pandoc)
* Removes docbook support
* Hooks in asciidoc
* Updates CI/CD

The asciidoc generator of choice is `asciidoctor`.

HTML generation of documentation has been removed.  Hence, the option of
`--enable-htmldoc` via `./configure` no longer exists.

Although this commit should be several small ones, getting this to build
incrementally is difficult.

Dockerfile

@@ -8,4 +8,4 @@ ENV GO111MODULE="on"
 COPY . /build
 WORKDIR /build
 
-RUN ./autogen.sh && ./configure --enable-golang && make -j4
+RUN ./autogen.sh && ./configure --enable-mandoc --enable-golang && make -j4

Makefile.am

@@ -23,7 +23,7 @@ SUBDIRS = \
 #    make distcheck2  # instead of make distcheck
 #    make distclean2  # instead of make distclean
 
-DISTCHECK_CONFIGURE_FLAGS = --enable-htmldoc
+DISTCHECK_CONFIGURE_FLAGS = --enable-mandoc
 
 distcheck2: distcheck
 	@banner="$(distdir).tar.gz - ready for distribution"; \

bin/Makefile.am

@@ -11,11 +11,7 @@ bin_SCRIPTS = fvwm-config fvwm-perllib \
 	fvwm-menu-xlock fvwm-menu-directory \
 	fvwm-menu-desktop
 
-man_MANS = \
-	fvwm-root.1 fvwm-config.1 fvwm-perllib.1 \
-	fvwm-convert-2.6.1 \
-	fvwm-menu-xlock.1 fvwm-menu-directory.1 \
-	fvwm-menu-desktop.1
+man_MANS = fvwm-menu-xlock.1
 
 LDADD = -L$(top_builddir)/libs $(X_LIBS) -lfvwm3 $(xpm_LIBS) $(Xcursor_LIBS) \
 	$(X_PRE_LIBS) -lXext -lX11 -lm $(X_EXTRA_LIBS) $(Xrender_LIBS) \
@@ -58,7 +54,7 @@ _fvwm-perllib.1: fvwm-perllib
 	rm -rf $$TMP)
 
 regenerate: \
-	_fvwm-menu-xlock.1 _fvwm-menu-directory.1 _fvwm-perllib.1
+	_fvwm-menu-xlock.1
 
 ## Create compatibility symlinks if available