Bug fixes, theme system

[gaetgu]

These commits do tons of stuff. Together, they have enabled me to use ved as my main editor working on ved (and other v stuff). Here's a quick rundown:

• Configurable settings (via ~/.ved/conf.toml)
• Fix editing at end of line (unable to edit at end without appending to it via A)
• Fix mouse to start and end of line, fixing behaviour that would create segfaults by trying to edit text that was not there
• Fix clicking below the end of the file (only possible on short file), which used to cause segfaults
• Handle window resizes. There is still more work to do here, but it is miles better than it was before
• Create an initial theming system inside of the settings file. Use any base16 them in a toml-friendly form.
  • There is still more work to do here, but not much that can be done without changing the highlighting system. Therefore, this will take back seat to many other changes

One known issue that is caused by this PR is that when opening ved on a 4k display, ved first draws the titlebar and other elements at a smaller size and readjusts to the screen size on the first call to draw().

[gaetgu]

For whatever reason, this PR is failing to build on the ubuntu check. I have confirmed that it builds on (arch x86) linux via a discord user, so I am not sure why that is happening. I am going to get a VM set up to see if I can replicate this behavior tomorrow.

[medvednikov]

Yeah a very strange error. Never seen it before.