☢️ WTF-1031 Support multiple simultaneous configurations (#1032)

* WTF-1031 Rename WtfApp.app to WtfApp.tviewApp

Signed-off-by: Chris Cummer <chriscummer@me.com>

* WTF-1031 Add scaffolding for main to support multiple WtfApp instances

Signed-off-by: Chris Cummer <chriscummer@me.com>

* WTF-1031 WIP

Signed-off-by: Chris Cummer <chriscummer@me.com>

* Remove common functionality from KeyboardWidget and into Base

Signed-off-by: Chris Cummer <chriscummer@me.com>

* Augment with some descriptive comments

Signed-off-by: Chris Cummer <chriscummer@me.com>

* Add full support for multiple app instances via the AppManager.

Still to do:

* Config support for multiple apps/multiple config files
* The ability to switch between apps

Signed-off-by: Chris Cummer <chriscummer@me.com>

* Move SetTerminal out of main and into its own file

Signed-off-by: Chris Cummer <chriscummer@me.com>

wtf/terminal.go

@@ -0,0 +1,22 @@
+package wtf
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/logrusorgru/aurora"
+	"github.com/olebedev/config"
+)
+
+// SetTerminal sets the TERM environment variable, defaulting to whatever the OS
+// has as the current value if none is specified.
+// See https://www.gnu.org/software/gettext/manual/html_node/The-TERM-variable.html for
+// more details.
+func SetTerminal(config *config.Config) {
+	term := config.UString("wtf.term", os.Getenv("TERM"))
+	err := os.Setenv("TERM", term)
+	if err != nil {
+		fmt.Printf("\n%s Failed to set $TERM to %s.\n", aurora.Red("ERROR"), aurora.Yellow(term))
+		os.Exit(1)
+	}
+}