Minus icons (#892)

* #891 reformat icondef.xml

* #891 client icons: merge psiplus into psi

* #891 icondef.xml: add same icons from plus

* #891 Remove PSI_PLUS links

* #891 Windows build: make same company for Psi and +

* #891 MacOS build: make same copyright for Psi and +

* #891 about: remove Psi+ tab and move authors to Psi

* about: remove tehnick from Thanks because he is listed in authors

* about: author XMPP link: show as a user, not chat join

* about: add XMPP link to chat

about: add link to chat

about: add link to chat

Author: stokito

client_icons.txt

@@ -59,8 +59,7 @@ pidgin pidgin,gaim
 pix-art pix-art
 poezio poezio,poez.io
 profanity profanity,www#profanity
-psi psi,psi-im
-psiplus psi+,psi-plus,psi-dev
+psi psi,psi-im,psi+,psi-plus,psi-dev
 qip qip,2010.qip.ru
 qutim qutim
 qxmpp-api qxmpp