Updated Meson configuration

- Added version and license metadata
- Configuration data to be used in configured files to set metadata
- Portable binary and directories in the main install directory
- Binary file installed in correct places for all supported platforms
- Freedesktop AppStream support
- Added missing files install rules

scripts/start.lua.in

@@ -0,0 +1,21 @@
+-- this file is used by lite-xl to setup the Lua environment when starting
+VERSION = "@PROJECT_VERSION@"
+MOD_VERSION = "1"
+
+SCALE = tonumber(os.getenv("LITE_SCALE")) or SCALE
+PATHSEP = package.config:sub(1, 1)
+
+EXEDIR = EXEFILE:match("^(.+)[/\\][^/\\]+$")
+if MACOS_RESOURCES then
+  DATADIR = MACOS_RESOURCES
+else
+  local prefix = EXEDIR:match("^(.+)[/\\]bin$")
+  DATADIR = prefix and (prefix .. '/share/lite-xl') or (EXEDIR .. '/data')
+end
+USERDIR = (os.getenv("XDG_CONFIG_HOME") and os.getenv("XDG_CONFIG_HOME") .. "/lite-xl")
+  or (HOME and (HOME .. '/.config/lite-xl') or (EXEDIR .. '/user'))
+
+package.path = DATADIR .. '/?.lua;' .. package.path
+package.path = DATADIR .. '/?/init.lua;' .. package.path
+package.path = USERDIR .. '/?.lua;' .. package.path
+package.path = USERDIR .. '/?/init.lua;' .. package.path