Fix parsing zoom level

[albfan]

I'm not really sure why this is happening, but on linux (arch linux updotade version January 2019) I need to remove trailing whitespace in order to parse zoom level

$ mono --version
Mono JIT compiler version 5.16.0 (makepkg/bb3ae37d71a Sat Dec  8 13:21:35 CET 2018)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           __thread
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          supported, not enabled.
	GC:            sgen (concurrent by default)

Anyway this a a change that cannot cause any harm, so please consider to apply.

NOTE: Didn't see any report of this, so maybe this is only my machine, or this is stopping people to use pinta.