Remove support for Travis CI

It is redundant with qpdf's main CI environment, which is Azure
Pipelines, but may soon be migrated to GitHub Actions.

.travis.yml

@@ -1,21 +0,0 @@
-language: cpp
-compiler: gcc
-sudo: require
-dist: xenial
-
-install:
-  - sudo apt-get update -qq
-  - sudo apt-get install -qq libgnutls28-dev docbook-xsl fop xsltproc less inkscape
-
-script:
-  - appimage/build-appimage
-
-after_success:
-  - cd appimage/build
-  - find ./appdir -executable -type f -exec ldd {} \; | grep " => /usr" | cut -d " " -f 2-3 | sort | uniq
-  - ls -l                       # for more debugging in Travis' log
-  - curl --upload-file ./qpdf*.AppImage https://transfer.sh/qpdf-git.$(git rev-parse --short HEAD)-x86_64.AppImage
-  - sha512sum ./qpdf*.AppImage*
-# Not ready to have travis automatically create github releases
-#  - wget -c https://github.com/probonopd/uploadtool/raw/master/upload.sh
-#  - bash upload.sh qpdf-*x86_64.AppImage*       # This should upload the .zsync file as well

README.md

@@ -2,8 +2,7 @@
 
 [![QPDF](logo/qpdf.svg)](http://qpdf.sourceforge.net)
 
-[![Azure Pipeline Build Status](https://dev.azure.com/qpdf/qpdf/_apis/build/status/qpdf.qpdf)](https://dev.azure.com/qpdf/qpdf/_build/latest?definitionId=5) [![Travis Build Status](https://travis-ci.org/qpdf/qpdf.svg?branch=master)](https://travis-ci.org/qpdf/qpdf)
-[![Total lgtm alerts](https://img.shields.io/lgtm/alerts/g/qpdf/qpdf.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/qpdf/qpdf/alerts/)
+[![Azure Pipeline Build Status](https://dev.azure.com/qpdf/qpdf/_apis/build/status/qpdf.qpdf)](https://dev.azure.com/qpdf/qpdf/_build/latest?definitionId=5) [![Total lgtm alerts](https://img.shields.io/lgtm/alerts/g/qpdf/qpdf.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/qpdf/qpdf/alerts/)
 [![Language grade on lgtm: C/C++](https://img.shields.io/lgtm/grade/cpp/g/qpdf/qpdf.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/qpdf/qpdf/context:cpp)
 
 This is the QPDF package.  Information about it can be found at http://qpdf.sourceforge.net.  The source code repository is hosted at GitHub: https://github.com/qpdf/qpdf.

TODO

@@ -1,9 +1,6 @@
 Candidates for upcoming release
 ===============================
 
-* Trivial fixes:
-  * Remove travisci
-
 * Quick issues:
   * #438: things written to stdout instead of stderr; --no-warn issues
   * #454: integer overflow

appimage/build-appimage

@@ -2,14 +2,12 @@
 
 # Copyright (c) 2019-2020 Jay Berkenbilt and Kurt Pfeifle
 #
-# This script is mainly meant to build an 'AppImage' from GitHub
-# sources of QPDF via Travis CI on an Ubuntu Trusty (14.04) LTS system
-# (see https://appimage.org/).
-#
-# But it also allows Linux users to build such an AppImage on their
-# own systems. Please read 'README.md' from the top level Git sources
-# to see what preconditions you must meet to build QPDF in general.
-# The same apply to build an AppImage. Then follow these three steps:
+# This script is used to build an 'AppImage' from GitHub sources of
+# QPDF (see https://appimage.org/). It is used in CI, but it also
+# allows Linux users to build such an AppImage on their own systems.
+# Please read 'README.md' from the top level Git sources to see what
+# preconditions you must meet to build QPDF in general. The same apply
+# to build an AppImage. Then follow these three steps:
 #
 #   1. Clone Git sources:  `git clone https://github.com/qpdf/qpdf.git git.qpdf`
 #   2. Change into git dir:  `cd git.qpdf`
@@ -33,8 +31,8 @@
 #   2. If you build the AppImage on a too recent Linux distribution,
 #      it may only work on the exact distribution you build it on. For
 #      an AppImage to work on a wide range of different distributions
-#      from the last 3-4 years if should be built on Ubuntu Trusty
-#      (14.04).
+#      from the last 3-4 years if should be built on the oldest
+#      supported Ubuntu LTS release.
 
 set -ex
 
@@ -172,7 +170,7 @@ else
     set +x
     echo ""
     echo " Running 'appimagetool' with '-n' parameter..."
-    echo " Reason: this does not seem to be a Travis CI build running on"
+    echo " Reason: this does not seem to be a build running on"
     echo " Ubuntu Trusty 14.04."
     echo " '-n' disables checking of AppStream data by the 'appstreamcli'"
     echo " utility since post-Trusty versions have incompatible changes."
@@ -183,13 +181,8 @@ fi
 # Set up a version string to include in the AppImage name
 MAJOR_QPDF_VERSION=$( ./appdir/usr/bin/qpdf --version | grep "qpdf version" | awk '{print $3}' )
 declare -a UPDATE_INFO
-if [ "$TRAVIS_JOB_NUMBER" != "" ]; then
-    VERSION=${MAJOR_QPDF_VERSION}-continuous-${TRAVIS_JOB_NUMBER}-$(date "+%Y-%m-%d")-git.$(git rev-parse --short HEAD)
-    # No update info supported for travis builds for now.
-else
-    VERSION=${MAJOR_QPDF_VERSION}
-    UPDATE_INFO=(-u "gh-releases-zsync|qpdf|qpdf|latest|qpdf-*x86_64.AppImage.zsync")
-fi
+VERSION=${MAJOR_QPDF_VERSION}
+UPDATE_INFO=(-u "gh-releases-zsync|qpdf|qpdf|latest|qpdf-*x86_64.AppImage.zsync")
 
 # Remove the default AppRun/symlink and use our own custom AppRun script
 rm appdir/AppRun; cp $top/appimage/AppRun appdir; chmod a+x appdir/AppRun