Reimplement dialog functionallity of the main window.
On branch master, changes to be committed:
	modified:   src/mainwindow.cpp
	modified:   src/mainwindow.h
	modified:   src/scintillaeditor.cpp
	modified:   src/scintillaeditor.h
Reimplement config handling and make it more stable for a possible release.
On branch master, changes to be committed:
	modified:   config/config.json
	modified:   src/generalconfig.cpp
	modified:   src/generalconfig.h
	modified:   src/leptonconfig.h
	modified:   src/leptonlexer.cpp
	modified:   src/mainwindow.cpp
	modified:   src/syntaxhighlightmanager.cpp
Set session file to be saved with other config files.
On branch master, changes to be committed:
	modified:   src/mainwindow.cpp
Improve session saving capabilities.
On branch master, changes to be committed:
	modified:   src/mainwindow.cpp