Unify required C++ standard and require C++ 17 for all modules. It does
not make a lot of sense to have different standard requirements in the
same project.
* use a macro to add resource files for executables and shared libraries
* use that macro to declare targets
* use that macro to set library/binary versioning
* use that macro to set target output name
* use a macro to create manpages and names
* Split out proxy headers and moved to public API to allow external
modules to be built.
* Split proxy into proxy library and proxy binary. The library
can be used by other applications and provides a simple API
* Improved channel passthrough, now all channels including dynamic
channels work.
* Extended module API to hook more events, improved module samples
* Cleaned up proxy code, removed global static variables used,
added WINPR_ASSERT
* Add support for C++ plugins.
* Seperate between a "module" and a "plugin": a module is a shared
library that exposes a function called "proxy_module_entry_point". This
function gets a parameter to `proxyPluginsManager*`, which can be used to
register plugins.
* Refine the API of the modules infrastructure:
* use proxyData* instead of rdpContext* when firing a hook or calling a filter.
* use clearer names.
* Instead of having to specify a path for each module to be loaded in
the configuration, the proxy now loads modules from specificed
directory, using the CMAKE variable PROXY_PLUGINDIR.
* Add an option to specify required plugins: plugins that the proxy
wouldn't start without having them fully loaded.
