[mouse] treat ctrl+click the same as shift+click

Some terminals capture shift+click so add ctrl+click as
an alternate way to highlight/mark lines.

NEWS.md

@@ -13,6 +13,10 @@ Interface Changes:
 * In the Gantt chart view, pressing `ENTER` will focus on
   the preview pane so you can scroll through messages
   with the selected Op ID.
+* With mouse mode enabled, `CTRL` can be used as an alternate
+  to `SHIFT` when clicking/dragging in the main view to
+  highlight lines.  A few terminals capture shift+clicks as a
+  way to select text and do not pass them to the application.
 
 Bug Fixes:
 * Log messages in formats with custom timestamp formats were

docs/source/ui.rst

@@ -428,6 +428,9 @@ elements will respond to mouse inputs:
 
 * clicking on the main view will move the cursor to the given
   row and dragging will scroll the view as needed;
+* :bkd:`Shift` (or :kbd:`CTRL`) clicking/dragging in the main
+  view will highlight lines and then toggle their bookmark
+  status on release;
 * double-clicking in the main view will select the underlying
   text and drag-selecting within a line will select the given
   text;

src/textview_curses.cc

@@ -184,13 +184,15 @@ const bookmark_type_t textview_curses::BM_SEARCH("search");
 const bookmark_type_t textview_curses::BM_META("meta");
 const bookmark_type_t textview_curses::BM_PARTITION("partition");
 
-textview_curses::textview_curses()
+textview_curses::
+textview_curses()
     : lnav_config_listener(__FILE__), tc_search_action(noop_func{})
 {
     this->set_data_source(this);
 }
 
-textview_curses::~textview_curses()
+textview_curses::~
+textview_curses()
 {
     this->tc_search_action = noop_func{};
 }
@@ -471,8 +473,10 @@ textview_curses::handle_mouse(mouse_event& me)
                     if (this->vc_enabled) {
                         if (this->tc_supports_marks
                             && me.me_button == mouse_button_t::BUTTON_LEFT
-                            && me.is_modifier_pressed(
-                                mouse_event::modifier_t::shift))
+                            && (me.is_modifier_pressed(
+                                    mouse_event::modifier_t::shift)
+                                || me.is_modifier_pressed(
+                                    mouse_event::modifier_t::ctrl)))
                         {
                             this->tc_selection_start = mc.mc_line;
                         }
@@ -1296,7 +1300,8 @@ text_sub_source::text_crumbs_for_line(int line,
 {
 }
 
-logfile_filter_state::logfile_filter_state(std::shared_ptr<logfile> lf)
+logfile_filter_state::
+logfile_filter_state(std::shared_ptr<logfile> lf)
     : tfs_logfile(std::move(lf))
 {
     memset(this->tfs_filter_count, 0, sizeof(this->tfs_filter_count));