Re-compress png images losslessly via Google zopflipng

[PeterDaveHello]

This will make the loading faster and save the bandwidth!

 Android_Robot_100.png                             | Bin 4075 -> 2779 bytes
 App-store-icon.png                                | Bin 5644 -> 5177 bytes
 GitHub-Mark-32px.png                              | Bin 1714 -> 606 bytes
 GuixSD-V.png                                      | Bin 7088 -> 5416 bytes
 JuiceSSH.png                                      | Bin 2698 -> 2312 bytes
 NetBSD-smaller-tb.png                             | Bin 5108 -> 2323 bytes
 Terminal-screenshot.png                           | Bin 12970 -> 11870 bytes
 alpinelinux-logo.png                              | Bin 10688 -> 7623 bytes
 arch.png                                          | Bin 1529 -> 993 bytes
 assets/img/glyphicons-halflings-white.png         | Bin 4352 -> 4346 bytes
 assets/img/glyphicons-halflings.png               | Bin 4352 -> 4346 bytes
 assets/img/termux.png                             | Bin 1147 -> 452 bytes
 blink_shell.png                                   | Bin 6122 -> 5020 bytes
 cdfs.png                                          | Bin 40958 -> 32068 bytes
 chrome.png                                        | Bin 8002 -> 6677 bytes
 debian.png                                        | Bin 1974 -> 1304 bytes
 dmg.png                                           | Bin 2402 -> 2034 bytes
 fedora.png                                        | Bin 3271 -> 2626 bytes
 freebsd.png                                       | Bin 4831 -> 4563 bytes
 gentoo.png                                        | Bin 3483 -> 3268 bytes
 gnome-screenshot.png                              | Bin 7371 -> 5346 bytes
 homebrew.png                                      | Bin 5309 -> 4173 bytes
 homebrew2.png                                     | Bin 5560 -> 4876 bytes
 macosx.png                                        | Bin 2281 -> 1390 bytes
 macports-logo-top.png                             | Bin 9559 -> 6618 bytes
 macports.png                                      | Bin 2295 -> 2037 bytes
 mosh-chrome.png                                   | Bin 2356 -> 2026 bytes
 mosh-screenshot.png                               | Bin 2663 -> 1735 bytes
 mosh.png                                          | Bin 12607 -> 9618 bytes
 openSUSE.png                                      | Bin 3450 -> 2250 bytes
 opencsw.png                                       | Bin 6532 -> 6060 bytes
 pdf.png                                           | Bin 1397 -> 1078 bytes
 terminal-shots/acs-gnome.png.2.png                | Bin 9042 -> 7324 bytes
 terminal-shots/acs-mosh.png.2.png                 | Bin 4483 -> 3461 bytes
 terminal-shots/acs-osx.png.2.png                  | Bin 21611 -> 19020 bytes
 terminal-shots/acs-xterm.png.2.png                | Bin 4997 -> 3966 bytes
 terminal-shots/firstcol-gnome.png.2.png           | Bin 8418 -> 6746 bytes
 terminal-shots/firstcol-mosh.png.2.png            | Bin 4611 -> 3531 bytes
 terminal-shots/firstcol-osx.png.2.png             | Bin 21488 -> 18878 bytes
 terminal-shots/firstcol-xterm.png.2.png           | Bin 5025 -> 3968 bytes
 terminal-shots/unicode-and-escape-gnome.png.2.png | Bin 8750 -> 6789 bytes
 terminal-shots/unicode-and-escape-mosh.png.2.png  | Bin 4729 -> 3604 bytes
 terminal-shots/unicode-and-escape-osx.png.2.png   | Bin 27075 -> 22592 bytes
 terminal-shots/unicode-and-escape-xterm.png.2.png | Bin 5122 -> 4012 bytes
 ubuntu.png                                        | Bin 2226 -> 1011 bytes
 windows.png                                       | Bin 665 -> 464 bytes
 xterm-screenshot.png                              | Bin 3145 -> 2072 bytes