Finish implementation of config file parsing

Still needs tests

tools/utils/paths/well_known.go

@@ -0,0 +1,65 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package paths
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"kitty/tools/utils"
+)
+
+var _ = fmt.Print
+
+type Ctx struct {
+	home, cwd string
+}
+
+func (ctx *Ctx) SetHome(val string) {
+	ctx.home = val
+}
+
+func (ctx *Ctx) SetCwd(val string) {
+	ctx.cwd = val
+}
+
+func (ctx *Ctx) HomePath() (ans string) {
+	ans = ctx.home
+	if ans == "" {
+		ans = utils.Expanduser("~")
+	}
+	return
+}
+
+func (ctx *Ctx) CwdPath() (ans string) {
+	ans = ctx.cwd
+	if ans == "" {
+		var err error
+		ans, err = os.Getwd()
+		if err != nil {
+			ans = "."
+		}
+	}
+	return
+}
+
+func abspath(path, base string) (ans string) {
+	return filepath.Join(base, path)
+}
+
+func (ctx *Ctx) Abspath(path string) (ans string) {
+	return abspath(path, ctx.CwdPath())
+}
+
+func (ctx *Ctx) AbspathFromHome(path string) (ans string) {
+	return abspath(path, ctx.HomePath())
+}
+
+func (ctx *Ctx) ExpandHome(path string) (ans string) {
+	if strings.HasPrefix(path, "~/") {
+		return ctx.AbspathFromHome(path)
+	}
+	return path
+}