chore: removes colorization from search

Deprecates `mgutz/ansi` and removes colorization from search as a first
step toward improving the functionality.

internal/sheet/search.go

@@ -3,13 +3,11 @@ package sheet
 import (
 	"regexp"
 	"strings"
-
-	"github.com/mgutz/ansi"
 )
 
 // Search searches for regexp matches in a cheatsheet's text, and optionally
 // colorizes matching strings.
-func (s *Sheet) Search(reg *regexp.Regexp, colorize bool) []Match {
+func (s *Sheet) Search(reg *regexp.Regexp) []Match {
 
 	// record matches
 	matches := []Match{}
@@ -30,13 +28,6 @@ func (s *Sheet) Search(reg *regexp.Regexp, colorize bool) []Match {
 			Text: strings.TrimSpace(line),
 		}
 
-		// colorize the matching text if so configured
-		if colorize {
-			m.Text = reg.ReplaceAllStringFunc(m.Text, func(matched string) string {
-				return ansi.Color(matched, "red+b")
-			})
-		}
-
 		// record the match
 		matches = append(matches, m)
 	}