Add new GUI themes and update documentation.

- Amber
- LCARS
- Orbital
- Weyland-Yutani
- Kanagawa Paper (dark mode extension)

Update help text to reflect additions.

docs/kte.1

@@ -146,15 +146,16 @@ When running the GUI frontend, you can control appearance via the generic
 command prompt (type "C-k ;" then enter commands):
 .TP
 .B : theme NAME
-Set the GUI theme. Available names: "eink", "everforest", "gruvbox", "kanagawa-paper", "nord", "old-book", "plan9", "solarized", "zenburn".
+Set the GUI theme. Available names: "amber", "eink", "everforest", "gruvbox", "kanagawa-paper", "lcars", "nord", "old-book", "orbital", "plan9", "solarized", "weyland-yutani", "zenburn".
 Compatibility aliases are also accepted: "gruvbox-dark", "gruvbox-light",
 "solarized-dark", "solarized-light", "eink-dark", "eink-light",
-"everforest-hard", "oldbook", "kanagawa", "kanagawa-light", "kanagawa-paper-light".
+"everforest-hard", "oldbook", "old-book-dark", "old-book-light",
+"kanagawa", "kanagawa-light", "kanagawa-paper-light", "vim-amber", "weyland".
 .TP
 .B : background MODE
 Set background mode for supported themes. MODE is either "light" or "dark".
-Themes that respond to background: eink, gruvbox, solarized. The
-"nord" and "plan9" themes do not vary with background.
+Themes that respond to background: eink, gruvbox, kanagawa-paper, old-book, solarized. The
+"lcars", "nord" and "plan9" themes do not vary with background.
 
 .SH CONFIGURATION
 The GUI reads a simple configuration file at