code cleanup: send book, not book id
code simplification
all fields declared in the same place
code created on ExternalFileOpener creation
fixed possible NPE
Merge branch 'master' into beta
do not show plugin dialog twice
Merge branch 'master' into beta
cleanup
Merge branch 'master' into beta
myNeedToSkipPlugin flag has gone
myIntentToOpen => myOpenBookIntent
synchronization with beta branch
new intent actions: CLOSE & PLUGIN_CRASH
Merge branch 'master' into beta