Improve cmdbar parsing and add -l replace flag

The -l flag to the replace command means "literal" and will treat
the search term literally instead of as a regular expression.

The command bar also now supports expanding environment variables
and running expressions through the shell and using the result
in the command.

cmd/micro/util_test.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"reflect"
 	"testing"
 )
 
@@ -67,56 +66,6 @@ func TestIsWordChar(t *testing.T) {
 	}
 }
 
-func TestJoinAndSplitCommandArgs(t *testing.T) {
-	tests := []struct {
-		Query  []string
-		Wanted string
-	}{
-		{[]string{`test case`}, `"test case"`},
-		{[]string{`quote "test"`}, `"quote \"test\""`},
-		{[]string{`slash\\\ test`}, `"slash\\\\\\ test"`},
-		{[]string{`path 1`, `path\" 2`}, `"path 1" "path\\\" 2"`},
-		{[]string{`foo`}, `foo`},
-		{[]string{`foo\"bar`}, `"foo\\\"bar"`},
-		{[]string{``}, ``},
-		{[]string{`"`}, `"\""`},
-		{[]string{`a`, ``}, `a `},
-		{[]string{``, ``, ``, ``}, `   `},
-		{[]string{"\n"}, `"\n"`},
-		{[]string{"foo\tbar"}, `"foo\tbar"`},
-	}
-
-	for i, test := range tests {
-		if result := JoinCommandArgs(test.Query...); test.Wanted != result {
-			t.Errorf("JoinCommandArgs failed at Test %d\nGot: %q", i, result)
-		}
-
-		if result := SplitCommandArgs(test.Wanted); !reflect.DeepEqual(test.Query, result) {
-			t.Errorf("SplitCommandArgs failed at Test %d\nGot: `%q`", i, result)
-		}
-	}
-
-	splitTests := []struct {
-		Query  string
-		Wanted []string
-	}{
-		{`"hallo""Welt"`, []string{`halloWelt`}},
-		{`"hallo" "Welt"`, []string{`hallo`, `Welt`}},
-		{`\"`, []string{`\"`}},
-		{`"foo`, []string{`"foo`}},
-		{`"foo"`, []string{`foo`}},
-		{`"\"`, []string{`"\"`}},
-		{`"C:\\"foo.txt`, []string{`C:\foo.txt`}},
-		{`"\n"new"\n"line`, []string{"\nnew\nline"}},
-	}
-
-	for i, test := range splitTests {
-		if result := SplitCommandArgs(test.Query); !reflect.DeepEqual(test.Wanted, result) {
-			t.Errorf("SplitCommandArgs failed at Split-Test %d\nGot: `%q`", i, result)
-		}
-	}
-}
-
 func TestStringWidth(t *testing.T) {
 	tabsize := 4
 	if w := StringWidth("1\t2", tabsize); w != 5 {