patch 8.2.0592: MS-Windows with VTP: cursor is not made invisible

Problem:    MS-Windows with VTP: cursor is not made invisible.
Solution:   Output the code to make the cursor visible or invisible. (Nobuhiro
            Takasaki, closes vim#5941)

patch 8.2.0591: MS-Windows: should always support IPv6

Problem:    MS-Windows: should always support IPv6
Solution:   Add build flag. (Ozaki Kiichi, closes vim#5944)

patch 8.2.0590: no 'backspace' value allows ignoring the insertion point

Problem:    No 'backspace' value allows ignoring the insertion point.
Solution:   Add the "nostop" and 3 values. (Christian Brabandt, closes vim#5940)

patch 8.2.0589: .bsd file type not recognized

Problem:    .bsd file type not recognized.
Solution:   Recognize .bsd as BSDL. (Daniel Kho, closes vim#5945)

patch 8.2.0588: Putty does not use "sgr" 'ttymouse' by default

Problem:    Putty does not use "sgr" 'ttymouse' by default.
Solution:   Make "sgr" the default for Putty. (Christian Brabandt,
            closes vim#5942)

patch 8.2.0587: compiler warning for unused variable

Problem:    Compiler warning for unused variable.
Solution:   Add UNUSED.

patch 8.2.0586: Vim9: # comment not sufficiently tested

Problem:    Vim9: # comment not sufficiently tested
Solution:   Check for preceding white space.

patch 8.2.0585: Vim9: # comment not recognized after :vim9script

Problem:    Vim9: # comment not recognized after :vim9script.
Solution:   Check script type. Make comment after ":echo" work.  And in
            several other places.

patch 8.2.0584: viminfo file uses obsolete function file_readable()

Problem:    Viminfo file uses obsolete function file_readable().
Solution:   Use filereadable(). (closes vim#5934)

patch 8.2.0583: Vim9: # comment not recognized in :def function

Problem:    Vim9: # comment not recognized in :def function.
Solution:   Recognize and skip # comment.