talkatu/talkatu

Change TalkatuAttachment to an interface and move it's implementation to TalkatuSimpleAttachment.

2020-07-21, Gary Kramlich
18152cf75bab
Change TalkatuAttachment to an interface and move it's implementation to TalkatuSimpleAttachment.

Also included the fix for TALKATU-82.

Testing Done:
Ran the demo in gdb with `G_DEBUG=fatal-warnings` and verified that attachments still worked as expected.

Bugs closed: TALKATU-82

Reviewed at https://reviews.imfreedom.org/r/24/
###############################################################################
# Options
###############################################################################
option(
'nls',
type : 'boolean', value : true,
description : 'Install translation files'
)
option(
'doc',
type : 'boolean', value : true,
description : 'build documentation with gtk-doc'
)
option(
'help2man',
type : 'boolean', value : true,
description : 'Whether or not to build man pages from --help output'
)
option(
'gobject-introspection',
type : 'boolean', value : true,
description : 'build gobject-introspection support'
)
option(
'tests',
type : 'boolean', value : true,
description : 'run unit tests'
)
option(
'vapi',
type : 'boolean', value : true,
description : 'Whether or not to build vapi files for gplugin'
)