v0.3.0

Many offsets/overflow bugs have been fixed. Many new navigation and UX features have been implemented:

• m now support finding the matching symbols over multiple lines
• the cursor style depends on the mode
• display a marker if some unsaved changes have been made
• ask confirmation before quitting if there's unsaved changes, and introduce the :wq force quit command
• support ~ expansion in the filename
• automatically translate a Tab to 4 spaces (thanks @ilmanzo !)
• automatically dump unsaved changes to a swap file, and restore it in case of a crash
• bo <filename> now opens a new/unsaved <filename> file