Add ComboBox::onChange() member function
ADd Entry::set/getSuffix() property
Add entry_suffix color for skin theme
Fix ui::Entry::onEntryChange: must be a virtual member function
Fix bug in ui::Entry::m_caret, after changing the widget's text we've to adjust the caret

This is to avoid "out of range" situations, where the caret is outdated
and doesn't correspond to the new widget's text length.
Add ui::IntEntry widget
Sort #includes in ui/entry.cpp file
Fix widgets borders using the "sunken_normal" SkinTheme part

Now the background color of the parent widget is used to draw the borders.
Rename old _ji_* functions
Add ContextBar in the MainWindow
Replace image_free() with UniquePtrs
Use new Entry suffixes in SpriteSizeCommand
Add popup to change the brush(pen) type in the ContextBar
Bigger hot region for IntEntry's popup window
Don't close IntEntry's popup in case of FOCUSLEAVE message
Fix IntEntry's popup if it's beyond the screen border