Misc. typos

Found using `codespell -q 3 -w --skip="*.svg,*.po,*.ts,./share/tutorials,./src/libavoid,./packaging/win32/languages,./man,./src/2geom" -I ../inkscape-whitelist.txt`
whereby whitelist file contained:
```
dum
iff
glight
substract
te
upto
```

2 files changed, 2 insertions, 2 deletions

diff --git a/src/ui/tools/gradient-tool.cpp b/src/ui/tools/gradient-tool.cpp
index 1735a78df..81d2f6a5b 100644
--- a/src/ui/tools/gradient-tool.cpp
+++ b/src/ui/tools/gradient-tool.cpp
@@ -636,7 +636,7 @@ bool GradientTool::root_handler(GdkEvent* event) {
                     }
                 } else if (this->item_to_select) {
                     if (over_line && line) {
-                        // Clicked on an existing gradient line, dont change selection. This stops
+                        // Clicked on an existing gradient line, don't change selection. This stops
                         // possible change in selection during a double click with overlapping objects
                     } else {
                         // no dragging, select clicked item if any
diff --git a/src/ui/tools/measure-tool.cpp b/src/ui/tools/measure-tool.cpp
index 24295e7cf..bd2964d94 100644
--- a/src/ui/tools/measure-tool.cpp
+++ b/src/ui/tools/measure-tool.cpp
@@ -1236,7 +1236,7 @@ void MeasureTool::showCanvasItems(bool to_guides, bool to_item, bool to_phantom,
         sp_canvas_item_destroy(measure_tmp_items[idx]);
     }
     measure_tmp_items.clear();
-    //TODO:Calculate the measure area for current lenght and origin
+    //TODO:Calculate the measure area for current length and origin
     // and use canvas->requestRedraw. In the calculation need a gap for outside text
     // maybe this remove the trash lines on measure use
     Inkscape::Preferences *prefs = Inkscape::Preferences::get();