Fix precedence and interference issues in config file

Resolves the issue from #396:

- The `klog config` subcommand now strictly only outputs values that are
specified in the file. There is no interference anymore with environment
variables (`$EDITOR` or `$NO_COLOR`).
- The `editor` entry from the config file now takes precedence over the
`$EDITOR` environment variable.
- Note: the `$NO_COLOR` environment variable, in contrast, still does
**not** take precedence over the `colour_scheme` entry from the config
file. That is to disable output colouring on the fly, for programmatic
invocations in scripted contexts.

Author: jotaen

README.md

@@ -23,7 +23,7 @@ klog is a plain-text file format and a command line tool for time tracking.
 If you have questions, feedback, feature ideas, or want to report something that’s not working properly,
 feel invited to [start a discussion](https://github.com/jotaen/klog/discussions).
 
-If you’d like to contribute code, please discuss your intended change beforehand. Please refrain from submitting unsolicited pull requests.
+If you’d like to contribute code, please discuss your intended change beforehand. Please refrain from submitting pull requests proactively.
 
 ## About
 

klog.go

@@ -3,11 +3,12 @@ package main
 import (
 	_ "embed"
 	"fmt"
+	"os"
+	"runtime"
+
 	"github.com/jotaen/klog/klog/app"
 	"github.com/jotaen/klog/klog/app/cli/util"
 	"github.com/jotaen/klog/klog/app/main"
-	"os"
-	"runtime"
 )
 
 //go:embed Specification.md
@@ -41,11 +42,7 @@ func main() {
 	}()
 
 	config := func() app.Config {
-		c, err := app.NewConfig(
-			app.FromDeterminedValues{NumCpus: runtime.NumCPU()},
-			app.FromEnvVars{GetVar: os.Getenv},
-			app.FromConfigFile{FileContents: configFile},
-		)
+		c, err := app.NewConfig(runtime.NumCPU(), os.Getenv, configFile)
 		if err != nil {
 			fail(util.PrettifyAppError(err, false), app.CONFIG_ERROR.ToInt())
 		}

klog/app/cli/config.go

@@ -1,11 +1,12 @@
 package cli
 
 import (
+	"path/filepath"
+	"strings"
+
 	"github.com/jotaen/klog/klog/app"
 	tf "github.com/jotaen/klog/klog/app/cli/terminalformat"
 	"github.com/jotaen/klog/klog/app/cli/util"
-	"path/filepath"
-	"strings"
 )
 
 type Config struct {
@@ -27,7 +28,7 @@ klog relies on file-based configuration to customise some of its default behavio
 
 Run 'klog config --location' to print the path of the folder where klog looks for the configuration.
 The config folder can contain one or both of the following files:
-  - '` + app.CONFIG_FILE_NAME + `': you can create this file manually to override some of klog’s default behaviour. You may use the output of the 'klog config' command as template for setting up this file, as its output is in valid syntax. 
+  - '` + app.CONFIG_FILE_NAME + `': you can create this file manually to override some of klog’s default behaviour. You may use the output of the 'klog config' command as template for setting up this file, as its output is valid .ini syntax. 
   - '` + app.BOOKMARKS_FILE_NAME + `': if you use the bookmarks functionality, then klog uses this file as database. You are not supposed to edit this file by hand! Instead, use the 'klog bookmarks' command to manage your bookmarks.
 
 You can customise the location of the config folder via environment variables. klog uses the following lookup precedence:

klog/app/cli/testcontext_test.go

@@ -1,14 +1,15 @@
 package cli
 
 import (
+	gotime "time"
+
 	"github.com/jotaen/klog/klog"
 	"github.com/jotaen/klog/klog/app"
 	"github.com/jotaen/klog/klog/app/cli/command"
 	tf "github.com/jotaen/klog/klog/app/cli/terminalformat"
 	"github.com/jotaen/klog/klog/parser"
 	"github.com/jotaen/klog/klog/parser/reconciling"
 	"github.com/jotaen/klog/klog/parser/txt"
-	gotime "time"
 )
 
 func NewTestingContext() TestingContext {
@@ -63,11 +64,11 @@ func (ctx TestingContext) _SetFileExplorers(cs []command.Command) TestingContext
 }
 
 func (ctx TestingContext) _SetFileConfig(configFile string) TestingContext {
-	fileCfg := app.FromConfigFile{FileContents: configFile}
-	err := fileCfg.Apply(ctx.config)
+	cfg, err := app.NewConfig(1, func(_ string) string { return "" }, configFile)
 	if err != nil {
 		panic(err)
 	}
+	ctx.config = &cfg
 	return ctx
 }