message: move to lib/message, update naming

Basically, move/rename lib/mu-message* to lib/mu-*.

Add the beginnings of a Message class.

lib/message/meson.build

@@ -0,0 +1,85 @@
+## Copyright (C) 2021 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software Foundation,
+## Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+
+lib_mu_message=static_library(
+  'mu-message',
+  [
+    'mu-message.cc',
+    'mu-message.hh',
+    'mu-contact.hh',
+    'mu-contact.cc',
+    'mu-document.cc',
+    'mu-document.hh',
+    'mu-fields.hh',
+    'mu-fields.cc',
+    'mu-flags.hh',
+    'mu-flags.cc',
+    'mu-priority.hh',
+    'mu-priority.cc'
+  ],
+  dependencies: [
+    glib_dep,
+    gmime_dep,
+    xapian_dep,
+    config_h_dep,
+    lib_mu_utils_dep],
+  install: false)
+
+# some of the libme headers include xapian
+xapian_incs = xapian_dep.get_pkgconfig_variable('includedir')
+lib_mu_message_dep = declare_dependency(
+  link_with: lib_mu_message,
+  include_directories:
+    include_directories(['.', '..', xapian_incs]))
+
+#
+# tests
+#
+
+test('test-contact',
+     executable('test-contact',
+		'mu-contact.cc',
+		install: false,
+		cpp_args: ['-DBUILD_TESTS'],
+		dependencies: [glib_dep, gmime_dep, lib_mu_message_dep]))
+
+test('test-document',
+     executable('test-document',
+		'mu-document.cc',
+		install: false,
+		cpp_args: ['-DBUILD_TESTS'],
+		dependencies: [glib_dep, gmime_dep, lib_mu_message_dep]))
+
+test('test-fields',
+     executable('test-fields',
+		'mu-fields.cc',
+		install: false,
+		cpp_args: ['-DBUILD_TESTS'],
+		dependencies: [glib_dep, gmime_dep, lib_mu_message_dep]))
+
+test('test-flags',
+     executable('test-flags',
+		'mu-flags.cc',
+		install: false,
+		cpp_args: ['-DBUILD_TESTS'],
+		dependencies: [glib_dep, gmime_dep, lib_mu_message_dep]))
+test('test-priority',
+     executable('test-priority',
+		'mu-priority.cc',
+		install: false,
+		cpp_args: ['-DBUILD_TESTS'],
+		dependencies: [glib_dep, gmime_dep, lib_mu_message_dep]))