message: Use sentence case for welcome buttons on Mac
  Use the same sentence case styling on all platforms. This is consistent
  with other Mac applications like Xcode etc.
diff: @@ -228,20 +228,20 @@ WelcomeScreenPanel::WelcomeScreenPanel(wxWindow *parent)
  sizer->Add(new ActionButton(
  this, wxID_OPEN,
  - MSW_OR_OTHER(_("Edit a translation"), _("Edit a Translation")),
  + _("Edit a translation"),
  _("Open an existing PO file and edit the translation.")),
  wxSizerFlags().PXBorderAll().Expand());
  sizer->Add(new ActionButton(
  this, XRCID("menu_new_from_pot"),
  - MSW_OR_OTHER(_("Create new translation"), _("Create New Translation")),
  + _("Create new translation"),
  _("Take an existing PO file or POT template and create a new translation from it.")),
  wxSizerFlags().PXBorderAll().Expand());
  #ifdef HAVE_HTTP_CLIENT
  sizer->Add(new ActionButton(
  this, XRCID("menu_open_crowdin"),
  - MSW_OR_OTHER(_("Collaborate on a translation with others"), _("Collaborate on a Translation with Others")),
  + _("Collaborate on a translation with others"),
  _("Download a file from Crowdin project, translate and sync your changes back.")),
  wxSizerFlags().PXBorderAll().Expand());
  sizer->Add(new LearnAboutCrowdinLink(this, _("What is Crowdin?")), wxSizerFlags().Right().Border(wxRIGHT, PX(8)));
  