The search string now can be highlighted. Add a global option to toggle shadows.

[DEVELOPMENT ENVIRONMENT]
* NEW: Search dialog: The option to highlight the search string is back. It takes "ignore case" and "word-only" options into account.
* NEW: Search dialog: A word now includes the "$" character.
* NEW: Option dialog: Add an option to toggle shadows.
* NEW: Project properties dialog: Add icons to the left panel.