Minor fixes identified through shellcheck and other tools (#350)

* fix whitespace

* fix spelling

* fix whitespace

* unify headers of tests

* fix some issues in tests, identified by shellcheck

* fix bash completions

bash completion files are not supposed to be executable

* fix some issues identified by shellcheck

Co-authored-by: Ali Karbassi <ali@karbassi.com>

tests/t2200-no-done-report-files.sh

@@ -1,5 +1,4 @@
 #!/bin/bash
-#
 
 test_description='todo.sh configuration with a sole todo.txt data file.
 
@@ -8,7 +7,7 @@ checks that no such empty files are created.
 '
 . ./test-lib.sh
 
-cat > test.cfg << EOF
+cat > test.cfg <<EOF
 export TODO_DIR=.
 export TODO_FILE="\$TODO_DIR/todo.txt"
 export DONE_FILE=/dev/null