Replace roff man pages with asciidoctor

This replaces the generation of man pages on project setup
by a on-demand generation via asciidoctor.
An exception are the man pages for the commands `day`, `month`, and `week`
which are simply redirects to the man page `timew-chart.1`. Those are now
static files in the Timewarrior repository.

A CMake find module to detect asciidoctor was added.
If asciidoctor is found, the targets `doc`, `man1`, and `man7` are created.
Those targets are also added to the default build target.

If asciidoctor is not available, the target `doc` is available, but it only
emits a message to install asciidoctor first.

Signed-off-by: Thomas Lauf <thomas.lauf@tngtech.com>

test/docker/archlinux

@@ -3,6 +3,7 @@ FROM archlinux/base
 RUN pacman -Sy --noconfirm archlinux-keyring
 RUN pacman -Syu --noconfirm
 RUN pacman -S --noconfirm \
+           asciidoctor \
            cmake \
            gcc \
            git \

test/docker/centos7

@@ -3,6 +3,7 @@ FROM centos:7
 RUN yum update -y
 RUN yum install -y epel-release centos-release-scl
 RUN yum install -y \
+        asciidoctor \
         cmake3 \
         devtoolset-7-gcc* \
         gcc-c++ \

test/docker/centos8

@@ -1,7 +1,8 @@
 FROM centos:8
 
-RUN yum update -y
-RUN yum install -y \
+RUN dnf update -y
+RUN dnf install -y \
+        ruby \
         cmake3 \
         gcc-c++ \
         git \
@@ -10,10 +11,9 @@ RUN yum install -y \
         python36 \
         python3-dateutil
 
-# Setup environment
-RUN echo "#!/bin/bash" >> /etc/profile.d/enable_env.sh ; \
-    echo "source scl_source enable devtoolset-7" >> /etc/profile.d/enable_env.sh ;
+RUN gem install asciidoctor
 
+# Setup environment
 RUN ln -sf /usr/bin/python3 /usr/bin/python
 
 ENV LC_ALL en_US.UTF-8

test/docker/debianstable

@@ -4,6 +4,7 @@ ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update
 RUN apt-get install -y \
+            asciidoctor \
             cmake \
             g++ \
             git \

test/docker/debiantesting

@@ -3,6 +3,7 @@ FROM debian:testing
 ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && apt-get install -y \
+            asciidoctor \
             cmake \
             fiu-utils=1.00-* \
             g++ \

test/docker/fedora31

@@ -2,7 +2,9 @@ FROM fedora:31
 
 RUN dnf update -y
 RUN dnf install -y \
+        asciidoctor \
         cmake \
+        findutils \
         gcc-c++ \
         glibc-locale-source \
         git \

test/docker/fedora32

@@ -2,7 +2,9 @@ FROM fedora:32
 
 RUN dnf update -y
 RUN dnf install -y \
+        asciidoctor \
         cmake \
+        findutils \
         gcc-c++ \
         glibc-locale-source \
         git \

test/docker/opensuse1500

@@ -8,8 +8,11 @@ RUN zypper install -y \
            make \
            man \
            python3 \
-           python3-dateutil
+           python3-dateutil \
+           ruby
 
+RUN gem install asciidoctor
+RUN update-alternatives --install /usr/bin/asciidoctor asciidoctor /usr/lib64/ruby/gems/2.5.0/gems/asciidoctor-2.0.12/bin/asciidoctor 10
 RUN update-alternatives --install /usr/bin/python python /usr/bin/python3 10
 ENV TZ=Europe/Berlin
 

test/docker/ubuntu1604

@@ -7,6 +7,7 @@ RUN apt-get update && \
     add-apt-repository -y ppa:ubuntu-toolchain-r/test
 RUN apt-get update && \
     apt-get install -y \
+            asciidoctor \
             cmake \
             gcc-snapshot \
             g++-6 \

test/docker/ubuntu1804

@@ -4,6 +4,7 @@ ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update
 RUN apt-get install -y \
+            asciidoctor \
             cmake \
             g++ \
             git \

test/docker/ubuntu2004

@@ -4,6 +4,7 @@ ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && yes | unminimize
 RUN apt-get install -y \
+            asciidoctor \
             cmake \
             g++ \
             git \