Use ASCII drawing for tree output

mkproj.1

@@ -120,23 +120,23 @@ Without any options, a full-featured project for a tool will be created, with
 the following layout:
 .Bd -literal
 mytool
-├── Makefile
-├── man
-│   └── man1
-│       └── mytool.1
-├── premake.make
-├── src
-│   ├── main.cpp
-│   ├── precomp.hpp
-│   ├── version.cpp
-│   └── version.hpp
-└── tests
-    ├── Makefile -> ../Makefile
-    ├── postmake.make
-    ├── premake.make
-    └── src
-        ├── main.cpp
-        └── precomp.hpp -> ../../src/precomp.hpp
+|-- Makefile
+|-- man
+|   `-- man1
+|       `-- mytool.1
+|-- premake.make
+|-- src
+|   |-- main.cpp
+|   |-- precomp.hpp
+|   |-- version.cpp
+|   `-- version.hpp
+`-- tests
+    |-- Makefile -> ../Makefile
+    |-- postmake.make
+    |-- premake.make
+    `-- src
+        |-- main.cpp
+        `-- precomp.hpp -> ../../src/precomp.hpp
 .Ed
 .Pp
 In this example, the project name is