Fix minor typos

src/menus/ClipMenus.cpp

@@ -344,7 +344,7 @@ TranslatableString ClipBoundaryMessage(
                First two %s are each replaced with the noun "start"
                or with "end", identifying and end of a clip,
                first and second numbers give the position of those clips in
-               a seqeunce of clips,
+               a sequence of clips,
                last number counts all clips,
                and the last string is the name of the track containing the
                clips.

src/menus/FileMenus.cpp

@@ -123,8 +123,8 @@ void OnOpen(const CommandContext &context )
    ProjectManager::OpenFiles(&project);
 }
 
-// JKC: This is like OnClose, except it emptys the project in place,
-// rather than createing a new empty project (with new toolbars etc).
+// JKC: This is like OnClose, except it empties the project in place,
+// rather than creating a new empty project (with new toolbars etc).
 // It does not test for unsaved changes.
 // It is not in the menus by default.  Its main purpose is/was for 
 // developers checking functionality of ResetProjectToEmpty().

src/menus/TrackMenus.cpp

@@ -407,7 +407,7 @@ class ASAProgress final : public SAProgress {
          mTotalCells = mFrames[0] * mFrames[1];
          work2 = mTotalCells * MATRIX_WORK_UNIT;
          mTotalWork += work2;
-         // arbitarily assume 60 iterations to fit smooth segments and
+         // arbitrarily assume 60 iterations to fit smooth segments and
          // per frame per iteration is SMOOTHING_WORK_UNIT
          if (smoothing) {
             work3 =