Configurable drop target directory on windows

[albertony]

Make drop target directory when --enable-drag-drop is active configurable with new option --drop-dir. Default is Windows Desktop as before.

Related to #969 and #970, in the sense that the improve the ability to run as a "portable app" (e.g. copy-deploy with local configuration).

[p12tic]

Just a single comment, looks good otherwise. Thanks!

[albertony]

Pushed an update (mutable instead of const).

One thing I noticed: The OSXScreen has its own m_dropTarget member string, with a non-virtual getter to return it. Not sure why it is not virtual?

barrier/src/lib/platform/OSXScreen.h

Line 102 in e66832c

const std::string& getDropTarget() const { return m_dropTarget; }

[albertony]

Another small change: Increased log level of a few central messages. There are already quite some "noice" with info messages just when moving cursor between screens ("leaving screen", "entering screen", "switch from x to y" etc), so I though a larger operation such as transferring a file would then also qualify for a info message.

By the way, the added sleep in the "Improve drag&drop stability on windows" commit is rather dirty, but seems the following lines were already in the same category. I got a lot of DEBUG: failed to get drag file name from OLE errors, to such a degree that drag-drop were basically useless. Adding this tiny sleep seems to improve it considerably, although i sometimes still get the error.

[p12tic]

Pushed an update (mutable instead of const).

One thing I noticed: The OSXScreen has its own m_dropTarget member string, with a non-virtual getter to return it. Not sure why it is not virtual?

barrier/src/lib/platform/OSXScreen.h

Line 102 in e66832c

const std::string& getDropTarget() const { return m_dropTarget; }

virtual automatically carries over for functions that override the virtual function from the base class. So it can be omitted in theory. In practice this is error prone and we should mark the overriding functions with override.

[p12tic]

Looks good, thanks.