Update engine.it.po

translate v0.18
Merge pull request #544 from dallatower/patch-1

Update engine.it.po
Czech engine translation by Zaraka
Do not unset/overwrite system environment CFLAGS/LDFLAGS

From hasufell on IRC
Merge pull request #547 from dorkster/bugfixes

Do not unset/overwrite system environment CFLAGS/LDFLAGS