Replace autotools with meson

To introduce much simpler build configuration which is also easier to
maintain.

src/meson.build

@@ -0,0 +1,24 @@
+config_h = configuration_data()
+config_h.set_quoted('VERSION', meson.project_version())
+config_h.set('BAUDRATE_CASES', baudrate_cases)
+configure_file(output: 'config.h', configuration: config_h)
+
+tio_sources = [
+  'error.c',
+  'log.c',
+  'main.c',
+  'options.c',
+  'misc.c',
+  'tty.c'
+  ]
+
+if tcgets2 != ''
+  tio_sources += 'setspeed2.c'
+endif
+
+executable('tio',
+  tio_sources,
+  install: true,
+)
+
+subdir('bash-completion')