contour 0.3.1.200

TL;DR This release is important as it's fixing some rendering bug. Most proudly however is to be presented the introduction of different vi-like input modes, that can be used to quickly copy'n'paste and move around in the grid buffer using the well known vi motions.

• Adds Vi-like input modes for improved selection and copy'n'paste experience.
• Adds contour executable to search path for spawned shell process on OS/X and Windows.
• Adds customizability to dim colors (#664).
• Adds the profile configuration option: draw_bold_text_with_bright_colors.
• Fixes CSI K accidentally removing line flags, e.g. line marks (#658).
• Fixes wrong-spacing rendering bug on some lines.
• Fixes assertion on font resize when a (Sixel) image is currently being rendered (#642).
• Fixes assertion on too quick shell terminations (#647).
• Fixes fallback shell execution on UNIX-like systems when the reuqested shell cannot be spawned (#647).
• Fixes selection being wrongly rendered when viewport is scrolled (#641).
• Fixes full-line selection not properly injecting linefeeds between the lines.
• Changes behaviour of full-line selection to include a trailing linefeed for the last line (#641).
• Changes behaviour of bold text to by rendered using normal colors by default (was forced to bright before, and is now configurable via draw_bold_text_with_bright_colors).