Add 16color theme (#66)

* Adding 16color theme

THEMES.md

@@ -2,6 +2,12 @@
 
 All available themes are only best effort ports by myself/ other users. If you find a theme to be weird/ wrong please open an issue/ pr.
 
+### 16color
+![normal](https://user-images.githubusercontent.com/13149513/104338605-e2f5b500-5520-11eb-9f6a-5e039025182e.jpg)
+![insert](https://user-images.githubusercontent.com/13149513/104338620-e5580f00-5520-11eb-9593-b59769d738a4.jpg)
+![visual](https://user-images.githubusercontent.com/13149513/104338631-e852ff80-5520-11eb-9341-0ecd87aed656.jpg)
+![replace](https://user-images.githubusercontent.com/13149513/104338654-eee17700-5520-11eb-9ff3-d2308d1243e5.jpg)
+
 ### dracula
 ![normal](https://user-images.githubusercontent.com/41551030/103468233-2d27ab00-4d57-11eb-8f3c-36426dd2f053.png)
 ![insert](https://user-images.githubusercontent.com/41551030/103468255-49c3e300-4d57-11eb-9e7a-2df1bf047465.png)

lua/lualine/themes/16color.lua

@@ -0,0 +1,53 @@
+-- =============================================================================
+-- Filename: lua/lualine/themes/16color.lua
+-- Author: shadman
+-- Credit itchyny, jackno (lightline)
+-- License: MIT License
+-- =============================================================================
+
+local M = {}
+
+local colors = {
+  black   = { '#000000', 0 },
+  maroon  = { '#800000', 1 },
+  green   = { '#008000', 2 },
+  olive   = { '#808000', 3 },
+  navy    = { '#000080', 4 },
+  purple  = { '#800080', 5 },
+  teal    = { '#008080', 6 },
+  silver  = { '#c0c0c0', 7 },
+  gray    = { '#808080', 8},
+  red     = { '#ff0000', 9 },
+  lime    = { '#00ff00', 10 },
+  yellow  = { '#ffff00', 11 },
+  blue    = { '#0000ff', 12 },
+  fuchsia = { '#ff00ff', 13 },
+  aqua    = { '#00ffff', 14 },
+  white   = { '#ffffff', 15 },
+}
+
+M.normal = {
+  a = { fg = colors.white, bg = colors.blue , gui = 'bold', },
+  b = { fg = colors.white, bg = colors.gray , },
+  c = { fg = colors.silver, bg = colors.black , }
+}
+
+M.insert = {
+  a = { fg = colors.white, bg = colors.green , gui = 'bold', },
+}
+
+M.visual = {
+  a = { fg = colors.white, bg = colors.purple , gui = 'bold', },
+}
+
+M.replace = {
+  a = { fg = colors.white, bg = colors.red , gui = 'bold', },
+}
+
+M.inactive = {
+  a = { fg = colors.silver, bg = colors.gray , gui = 'bold', },
+  b = { fg = colors.gray, bg = colors.black , },
+  c = { fg = colors.silver, bg = colors.black , },
+}
+
+return M