shared: Begin db migration logic

Issue: #26

shared/migrations/1.sql

@@ -0,0 +1,6 @@
+CREATE TABLE file(id INTEGER PRIMARY KEY, path varchar(4096) UNIQUE, mtime integer, size integer, filetype char(1));
+CREATE TABLE content(id INTEGER PRIMARY KEY, fileid INTEGER REFERENCES file (id) ON DELETE CASCADE, page integer, content text);
+CREATE VIRTUAL TABLE content_fts USING fts5(content, content='content', content_rowid='id');
+CREATE TRIGGER contents_ai AFTER INSERT ON content BEGIN  INSERT INTO content_fts(rowid, content) VALUES (new.id, new.content); END;
+CREATE TRIGGER contents_ad AFTER DELETE ON content BEGIN  INSERT INTO content_fts(content_fts, rowid, content) VALUES('delete', old.id, old.content); END;
+CREATE TRIGGER contents_au AFTER UPDATE ON content BEGIN  INSERT INTO content_fts(content_fts, rowid, content) VALUES('delete', old.id, old.content);  INSERT INTO content_fts(rowid, content) VALUES (new.id, new.content); END;

shared/migrations/migrations.qrc

@@ -0,0 +1,5 @@
+<RCC>
+    <qresource prefix="/looqs-migrations">
+        <file>1.sql</file>
+    </qresource>
+</RCC>