Tab Bar and Other Minor Improvements

This is a set of small suggestions!

• Mousewheel Scrollable Tab List. ( When the mouse is over the tab bar, you can scroll the mousewheel up to scroll the tab bar left and down to scroll the tab bar right. )
• Only show the filename in the tablist, not the full path. ( It takes up a lot of space in the tab bar and is redundant thanks to the status bar. )
• Replace the + symbol with < and > as appropriate to show that there are more tabs than fit onscreen.
• A one line margin below the tab bar. ( I've accidentally clicked on text when I meant to click on a tab. )
• A title bar that can be toggled and is stylable in the line above the tab bar. ( > set titlebar on|off ) The title bar would read "μ micro v.{version #}" It's such a small thing but I'd like it.

These are largely aesthetic changes and not a big priority, but it'd be cool.

Currently using:
Commit hash: 7b03f5b

The issue bundles five tab-bar and title-bar improvements without naming files or tests. Start by locating the tab-bar and title-bar entry points in the repository, then decide whether the suggestions should be split into separate changes. Done means the selected behavior is implemented and verified across the affected terminal UI interactions.