Generate labels with pangocairo (#8)

Goal of this PR is to have some basic labels generated with pangocairo
- size of the canvas should be matching the input text and grow/shrink accordingly
- basic formatting options like fontsize and align should be working

Reviewed-on: moritz/ptouch-prnt#8

.vscode/launch.json

@@ -10,9 +10,21 @@
       "request": "launch",
       "program": "${workspaceFolder}/builddir/ptprnt",
       "args": [
-        "-t Hello"
+        "-t i"
       ],
-      "cwd": "${fileDirname}",
+      "stopAtEntry": false,
+      "cwd": "${workspaceFolder}",
+      "environment": [],
+      "externalConsole": false,
+      "MIMode": "gdb",
+      "miDebuggerPath": "/usr/bin/gdb",
+      "setupCommands": [
+        {
+          "description": "Automatische Strukturierung und Einrückung für \"gdb\" aktivieren",
+          "text": "-enable-pretty-printing",
+          "ignoreFailures": true
+        }
+      ]
     }
   ]
 }