Refactor search queries: Introduced QSSQuery

Purpose is to seperate certain logic from SQLite and generalize it more.
Even though we only have Sqlite atm, in general the database layers
must be stupid as possible, while QSSQuery should do most of the hard work.

Fixes in Tokenizer logic.
Switched to C++17.

shared/shared.pro

@@ -11,6 +11,7 @@ QT       -= gui
 TARGET = shared
 TEMPLATE = lib
 CONFIG += staticlib
+CONFIG += c++17
 
 # The following define makes your compiler emit warnings if you use
 # any feature of Qt which has been marked as deprecated (the exact warnings
@@ -24,12 +25,15 @@ DEFINES += QT_DEPRECATED_WARNINGS
 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
 
 SOURCES += sqlitesearch.cpp \
-    qssgeneralexception.cpp
+    qssgeneralexception.cpp \
+    qssquery.cpp
 
 HEADERS += sqlitesearch.h \
     filedata.h \
     searchresult.h \
-    qssgeneralexception.h
+    qssgeneralexception.h \
+    token.h \
+    qssquery.h
 unix {
     target.path = /usr/lib
     INSTALLS += target