Only display the "Center Me" button when the view is not centered

There's no need to have the button there obscuring the map when it would have
no effect to press it.
Update Marathi translation
Update Hindi translation
fix startup NPE
hide zoom buttons when opening metrics sidebar
Merge pull request #1239 from cascheberg/fix

Fix NPE startup crash
Merge pull request #1231 from keverets/hide-centerme-button

Only display the "Center Me" button when the view is not centered
Merge pull request #1241 from cascheberg/fix-metrics

@cascheberg Hide map zoom buttons when opening metrics sidebar
Merge pull request #1235 from vinitraje/dev

@vinitraje Update Hindi & Marathi translations
Added global makeLogTag function to ensure tags are 23 characters or
less. Android has a soft limit on this of 23 characters, and depending
on the logging function used, it may or may not enforce this limit.
onDestroy, cancel the alarm
Change isSupported -> isSupportedOnThisDevice, and make
isSupportedOnThisDevice use the existing mTelephonyManager if available.
Merge pull request #1243 from garvankeeley/cellscanner-move-null-check

Sync Fennec code with stumbler github
sync zh-CN translations with en-US strings
fix log no_truncate feature
Merge pull request #1246 from cascheberg/fix

@cascheberg Fix untruncated log feature
Merge pull request #1230 from Aishraj/dev

@Aishraj Adding Nepali Strings.
Merge pull request #1245 from l-hedgehog/zh-cn

@l-hedgehog sync zh-CN translations with en-US strings