Store connection configuration as key value pairs

Add migration for the sqlite database.
Because the Qt SQL library is a bit hard to work with use sqlite through custom wrapper.

core/core.pro

@@ -5,7 +5,6 @@
 #-------------------------------------------------
 
 QT       -= gui
-QT       += sql
 
 TARGET = core
 TEMPLATE = lib
@@ -21,16 +20,13 @@ error( "Couldn't find the common.pri file!" )
 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
 
 SOURCES += my_boost_assert_handler.cpp \
-    KeyStrengthener.cpp \
     SqlLexer.cpp \
-    PasswordManager.cpp \
     CsvWriter.cpp \
     BackupFormatModel.cpp \
     ExplainTreeModelItem.cpp \
     jsoncpp.cpp
 
-HEADERS += PasswordManager.h \
-    KeyStrengthener.h \
+HEADERS += \
     SqlLexer.h \
     ScopeGuard.h \
     CsvWriter.h \