Fixed the way Windows usernames are processed by the plugin.
On Windows, some usernames may contain Unicode characters (for example Greek),
which mess up the avrdude command execution. To avoid this, the command is built
using relative paths and then the command string is written to a batch file.
Executing the batch file in the plugin directory causes no problems.
Added debugging verbosity levels

Debug level 1
This level prints out only basic information such as the avrdude command and the output stored in the output file.
Debug level 2
This level prints out all messages that level 1 prints as well as some more information for uploading and communication with the serial ports.
Debug level 3
This level prints out all messages that the 2 previous levels print and also a message for almost every function that is called during program execution. The output of this level is stored in a .txt file that can be found in the plugin folder.
Added avrdude verbose output flag
Merge branch 'Windows-usernames' into dev

Conflicts:
	Codebendercc/CodebenderccAPI.cpp
	Codebendercc/CodebenderccAPI.h
Remove merge statements.