[Frontend-STFL] Wrap lines correctly (closes #849).

Rewrite the line-wrapping code of STFL not to count style specifications toward
the line length and to wrap at word boundaries if possible.
[Engine, Frontend-STFL] Implemented 16 colors palette of the Linux console
Merge remote-tracking branch 'github/RavuAlHemio/feature/#849_stfl_text_wrap' into experiments/stfl_color_support
[Frontend-STFL] Fixed build on .NET 3.5 profile
[Frontend-STFL(|-Tests)] Handle escaped < when breaking.

STFL escapes < characters as <>. Handle those cases correctly.
[Frontend-STFL] Improve wrapping performance.

Don't recalculate information we already know.
[Engine] Implemented cache for TextColorTools.GetNearestColor()
[Frontend-STFL] Improved estimated length calculation in TextView.Resize()
[Frontend(-GNOME|-STFL] Moved /generate_messages to Frontend library
[Frontend-STFL] Added performance benchmark of TextView.Resize()
Merge branch 'experiments/stfl_color_support'