fix macOS travis CI

.travis_macos.sh

@@ -6,6 +6,8 @@ brew update > /dev/null
 # Use Qt5.9.3 instead of 5.10
 cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula
 git checkout 13d52537d1e0e5f913de4639012 qt.rb
+sed -i '' 's/:mysql/"mysql"/' qt.rb
+sed -i '' 's/:postgresql/"postgresql"/' qt.rb
 brew install qt
 
 QTDIR="/usr/local/opt/qt"

src/vmathjaxinplacepreviewhelper.cpp

@@ -230,7 +230,7 @@ void VMathJaxInplacePreviewHelper::textToHtmlFinished(int p_identitifer,
                                                       int p_timeStamp,
                                                       const QString &p_html)
 {
-    if (m_documentID != p_identitifer || m_timeStamp != p_timeStamp) {
+    if (m_documentID != p_identitifer || m_timeStamp != (TS)p_timeStamp) {
         return;
     }