Fix bugs with the cut-language server in the vs code extension

[dakaa16]

The cut-language is unstable. The following bugs should be fixed:

• BEFORE-EACH with a hyphen is not being recognized, so it is not colored. (Note that both 'BEFORE EACH' and 'BEFORE-EACH' are valid)
• AFTER-EACH with a hyphen is not being recognized, so it is not colored. (Note that both 'AFTER EACH' and 'AFTER-EACH' are valid)
• END-BEFORE and END-AFTER are seen as 'unclosed' and will always show an error. The error should only show up on AFTER EACH or BEFORE EACH when they are not closed with END-AFTER or END-BEFORE.
• Text inside a string is not ignored by the syntax check, so the following mock shows an error, due to the word 'MOCKED' inside the string:

           MOCK PARAGRAPH 300-CHANGE-1
              EVALUATE VALUE-1
              WHEN "Hello"
                MOVE "MOCKED" TO VALUE-1
              WHEN OTHER
                MOVE "mocked" TO VALUE-1
              END-EVALUATE
           END-MOCK