Score file reading: fix bar line span for non-5-line staves.

While reading a score, if a staff is found with number of lines != 5 and no explicit bar line span set (i.e. default bar line span), the bar line span remains set as for a 5-line staff.
Fix StaffType::operator==

For TAB_STAFF_GROUP, the equality operator does not check all the member variables (does not call isSameStructure())

Also, simplified some duplicate tests.
In staff type dlg box, only displays staff types from groups relevant to staff instrument.

Also removes the default guitar string data, which does not make sense for non-stringed instruments (stringed instruments are assumed to have proper string data in instruments.xml anyway)
Add comments
Fix tab order and buddies of staff type dlg box
Renamed stafftype.ui to editstafftype.ui
Apply template filtering to instrument wizard too.

Also fix selection of current template in instrument type combo box.
Fix build error.
Fix tests (maybe...)
More test fixes...
Fix crash when adding to the Instrument wizard a new instrument without an associated preset.
fix 'German accent'
ignore some backup- and temp. files

created by vim and QtCreator
fix stray rest
add a comment

same as the one in the correspoding .h file
make it C++ and don't translate

translating doesn't work (not this way at least) and won't happen anyway
as the translation mechanism is set up only later in the code, after the
use of the usage() function.
Remove the mention of an option that (no longer?) exists
fix #25755: avoid duplicates in plugin help

and add two missing ones. Also remove a 'plugin comment' from a .cpp
file, where it doesn't serve any purpose anyway (but at first tricked me
into believing this were the the culprit for the duplicate)
improve mtest

unified diffs are much easier to read
update file format history

as per http://musescore.org/en/developers-handbook/version-information
small optimization: call spatium() only once

and fix indentation