add a filesep option to configure file seperator

Mentioned in #47.

app.go

@@ -110,7 +110,7 @@ func (app *app) exportVars() {
 
 	marks := app.nav.currMarks()
 
-	envFiles := strings.Join(marks, ":")
+	envFiles := strings.Join(marks, gOpts.filesep)
 
 	os.Setenv("f", envFile)
 	os.Setenv("fs", envFiles)

comp.go

@@ -58,6 +58,7 @@ var (
 		"preview!",
 		"scrolloff",
 		"tabstop",
+		"filesep",
 		"ifs",
 		"previewer",
 		"shell",

doc.go

@@ -53,6 +53,7 @@ The following options can be used to customize the behavior of lf:
 	preview    bool    (default on)
 	scrolloff  int     (default 0)
 	tabstop    int     (default 8)
+	filesep    string  (default ":")
 	ifs        string  (default "") (not exported if empty)
 	previewer  string  (default "") (not filtered if empty)
 	shell      string  (default "$SHELL")

docstring.go

@@ -57,6 +57,7 @@ The following options can be used to customize the behavior of lf:
     preview    bool    (default on)
     scrolloff  int     (default 0)
     tabstop    int     (default 8)
+    filesep    string  (default ":")
     ifs        string  (default "") (not exported if empty)
     previewer  string  (default "") (not filtered if empty)
     shell      string  (default "$SHELL")

eval.go

@@ -69,6 +69,8 @@ func (e *setExpr) eval(app *app, args []string) {
 			return
 		}
 		gOpts.tabstop = n
+	case "filesep":
+		gOpts.filesep = e.val
 	case "ifs":
 		gOpts.ifs = e.val
 	case "previewer":

opts.go

@@ -8,6 +8,7 @@ var gOpts struct {
 	preview   bool
 	scrolloff int
 	tabstop   int
+	filesep   string
 	ifs       string
 	previewer string
 	shell     string
@@ -25,6 +26,7 @@ func init() {
 	gOpts.preview = true
 	gOpts.scrolloff = 0
 	gOpts.tabstop = 8
+	gOpts.filesep = ":"
 	gOpts.shell = envShell
 	gOpts.showinfo = "none"
 	gOpts.sortby = "natural"