CI and custom build script utilities

- macOS DMG image using AppDMG with custom background
- Linux AppImage
- Windows MSYS2 packaging
- Source code tarball including subprojects source code
- LHelper compatible build script

scripts/build.sh

@@ -0,0 +1,103 @@
+#!/bin/bash
+set -ex
+
+if [ ! -e "src/api/api.h" ]; then
+  echo "Please run this script from the root directory of Lite XL."
+  exit 1
+fi
+
+show_help(){
+  echo
+  echo "Usage: $0 <OPTIONS>"
+  echo
+  echo "Available options:"
+  echo
+  echo "-b --builddir DIRNAME     Sets the name of the build directory (not path)."
+  echo "                          Default: 'build'."
+  echo "-p --prefix               Install directory prefix. Mandatory."
+  echo "-s --static               Specify if building using static libraries"
+  echo "                          by using lhelper tool."
+  echo
+}
+
+install_lhelper() {
+  if [[ ! -d lhelper ]]; then
+    git clone https://github.com/franko/lhelper.git
+    pushd lhelper; bash install-github; popd
+
+    if [[ "$OSTYPE" == "darwin"* ]]; then
+      CC=clang CXX=clang++ lhelper create lite-xl -n
+    else
+      lhelper create lite-xl -n
+    fi
+  fi
+
+  # Not using `lhelper activate lite-xl`
+  source "$(lhelper env-source lite-xl)"
+
+  lhelper install freetype2
+  lhelper install sdl2 2.0.14-wait-event-timeout-1
+  lhelper install pcre2
+
+  # Help MSYS2 to find the SDL2 include and lib directories to avoid errors
+  # during build and linking when using lhelper.
+  if [[ "$OSTYPE" == "msys" ]]; then
+    CFLAGS=-I${LHELPER_ENV_PREFIX}/include/SDL2
+    LDFLAGS=-L${LHELPER_ENV_PREFIX}/lib
+  fi
+}
+
+build() {
+  CFLAGS=$CFLAGS LDFLAGS=$LDFLAGS meson setup \
+    --buildtype=release \
+    --prefix "$PREFIX" \
+    --wrap-mode=forcefallback \
+    "${BUILD_DIR}"
+
+  meson compile -C build
+}
+
+BUILD_DIR=build
+STATIC_BUILD=false
+
+for i in "$@"; do
+  case $i in
+    -h|--belp)
+      show_help
+      exit 0
+      ;;
+    -b|--builddir)
+      BUILD_DIR="$2"
+      shift
+      shift
+      ;;
+    -p|--prefix)
+      PREFIX="$2"
+      shift
+      shift
+      ;;
+    -s|--static)
+      STATIC_BUILD=true
+      shift
+      ;;
+    *)
+      # unknown option
+      ;;
+  esac
+done
+
+if [[ -n $1 ]]; then
+  show_help
+  exit 1
+fi
+
+if [[ -z $PREFIX ]]; then
+  echo "ERROR: prefix argument is missing."
+  exit 1
+fi
+
+if [[ $STATIC_BUILD == true ]]; then
+  install_lhelper
+fi
+
+build