Added Gotham theme

Based on [vim-gotham](https://github.com/whatyouhide/vim-gotham)

data/themes.yml

@@ -208,3 +208,6 @@
 -
   :name: 'Douglas Rain'
   :colors: '#EDECEB,#E3E3E3,#DA552F,#FFFFFF,#D6D6D6,#534540,#DA552F,#DA552F'
+-
+  :name: 'Gotham'
+  :colors: '#0A0F14,#10151B,#265360,#D4EBE9,#D26939,#9BD1CE,#EDB54B,#C33027'