Lossless recompress of images with pngcrush+zopfli

And tweak RTF.

build_tools/osx_package_resources/welcome.rtf

@@ -1,15 +1,16 @@
-{\rtf1\ansi\ansicpg1252\cocoartf1187\cocoasubrtf370
-{\fonttbl\f0\fswiss\fcharset0 Helvetica;\f1\fnil\fcharset0 Monaco;}
+{\rtf1\ansi\ansicpg1252\cocoartf1485\cocoasubrtf410
+{\fonttbl\f0\fnil\fcharset0 HelveticaNeue;\f1\fnil\fcharset0 Menlo-Regular;}
 {\colortbl;\red255\green255\blue255;}
+{\*\expandedcolortbl;\csgenericrgb\c100000\c100000\c100000;}
 {\info
 {\author dlkfjslfjsfdlkfk}}\margl1440\margr1440\vieww10800\viewh8400\viewkind0
-\pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural
+\pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\pardirnatural\partightenfactor0
 
-\f0\fs30 \cf0 The fish shell is a smart and user friendly command line shell. For more information, visit {\field{\*\fldinst{HYPERLINK "http://fishshell.com"}}{\fldrslt http://fishshell.com}}.\
+\f0\fs30 \cf0 Fish is a smart and user friendly command line shell. For more information, visit {\field{\*\fldinst{HYPERLINK "https://fishshell.com"}}{\fldrslt https://fishshell.com}}\
 \
-fish will be installed into
+fish will be installed into 
 \f1\fs26 /usr/local/
-\f0\fs30 , and fish will be added to
+\f0\fs30 , and fish will be added to 
 \f1\fs26 /etc/shells
 \f0\fs30  if necessary.\
 \