Add colorcolumn option

Fixes #333

For example: `> set colorcolumn 80`.

cmd/micro/settings.go

@@ -165,6 +165,7 @@ func GetOption(name string) interface{} {
 func DefaultGlobalSettings() map[string]interface{} {
 	return map[string]interface{}{
 		"autoindent":   true,
+		"colorcolumn":  float64(0),
 		"colorscheme":  "zenburn",
 		"cursorline":   true,
 		"ignorecase":   false,
@@ -187,6 +188,7 @@ func DefaultGlobalSettings() map[string]interface{} {
 func DefaultLocalSettings() map[string]interface{} {
 	return map[string]interface{}{
 		"autoindent":   true,
+		"colorcolumn":  float64(0),
 		"cursorline":   true,
 		"filetype":     "Unknown",
 		"ignorecase":   false,

cmd/micro/view.go

@@ -806,7 +806,16 @@ func (v *View) DisplayView() {
 				}
 			}
 			if screenX-v.x-v.leftCol+i >= v.lineNumOffset {
-				v.drawCell(screenX-v.leftCol+i, screenY, ' ', nil, lineStyle)
+				colorcolumn := int(v.Buf.Settings["colorcolumn"].(float64))
+				if colorcolumn != 0 && screenX-v.leftCol+i == colorcolumn-1 {
+					if style, ok := colorscheme["color-column"]; ok {
+						fg, _, _ := style.Decompose()
+						lineStyle = lineStyle.Background(fg)
+					}
+					v.drawCell(screenX-v.leftCol+i, screenY, ' ', nil, lineStyle)
+				} else {
+					v.drawCell(screenX-v.leftCol+i, screenY, ' ', nil, lineStyle)
+				}
 			}
 		}
 	}

runtime/colorschemes/atom-dark-tc.micro

@@ -17,3 +17,4 @@ color-link current-line-number "#656866,#1D1F21"
 color-link gutter-error "#FF4444,#1D1F21"
 color-link gutter-warning "#EEEE77,#1D1F21"
 color-link cursor-line "#2D2F31"
+color-link color-column "#2D2F31"

runtime/colorschemes/bubblegum.micro

@@ -17,3 +17,4 @@ color-link gutter-error "197,231"
 color-link gutter-warning "134,231"
 color-link line-number "246,254"
 color-link cursor-line "254"
+color-link color-column "254"

runtime/colorschemes/gruvbox.micro

@@ -13,3 +13,4 @@ color-link todo "bold 223,235"
 color-link line-number "243,237"
 color-link current-line-number "172,237"
 color-link cursor-line "237"
+color-link color-column "237"

runtime/colorschemes/monokai.micro

@@ -17,3 +17,4 @@ color-link current-line-number "#AAAAAA,#282828"
 color-link gutter-error "#CB4B16,#282828"
 color-link gutter-warning "#E6DB74,#282828"
 color-link cursor-line "#323232"
+color-link color-column "#323232"

runtime/colorschemes/simple.micro

@@ -14,3 +14,4 @@ color-link current-line-number "red"
 color-link gutter-error ",red"
 color-link gutter-warning "red"
 color-link cursor-line "white"
+color-link color-column "white"

runtime/colorschemes/solarized-tc.micro

@@ -16,3 +16,4 @@ color-link current-line-number "#586E75,#002833"
 color-link gutter-error "#003541,#CB4B16"
 color-link gutter-warning "#CB4B16,#002833"
 color-link cursor-line "#003541"
+color-link color-column "#003541"

runtime/colorschemes/solarized.micro

@@ -15,3 +15,4 @@ color-link current-line-number "brightgreen,default"
 color-link gutter-error "black,brightred"
 color-link gutter-warning "brightred,default"
 color-link cursor-line "black"
+color-link color-column "black"

runtime/colorschemes/zenburn.micro

@@ -17,4 +17,5 @@ color-link line-number "248,238"
 color-link gutter-error "237,174"
 color-link gutter-warning "174,237"
 color-link cursor-line "238"
+color-link color-column "238"
 color-link current-line-number "188,237"

runtime/help/colors.md

@@ -108,6 +108,8 @@ Here is a list of the colorscheme groups that you can use:
 * gutter-error
 * gutter-warning
 * cursor-line
+* current-line-number
+* color-column
 
 Colorschemes can be placed in the `~/.config/micro/colorschemes` directory to be used.
 

runtime/help/options.md

@@ -23,6 +23,11 @@ Here are the options that you can set:
     You can read more about micro's colorschemes in the `colors` help topic
     (`help colors`).
 
+* `colorcolumn`: if this is not set to 0, it will display a column at the specified
+   column. This is useful if you want column 80 to be highlighted special for example.
+
+	default value: `0`
+
 * `tabsize`: sets the tab size to `option`
 
 	default value: `4`