when serializing dependencies, make sure it takes only the master language

[larshp]

this should kick in,
https://github.com/larshp/abapGit/blob/master/src/objects/zcl_abapgit_object_msag.clas.abap#L222

[larshp]

tested, it currently takes all languages

[ed-holland]

Check the xml file of a MSAG. It is only generating the Master Language for the messages.
What makes the fill big, is the dependent long Text.

For MSAG's outside of our development package, the long texts should not be downloaded.
If it is our development package, it should only do the requested language (if setting say so).

[ed-holland]

There is more that is not needed for dependencies.

[larshp]

for longtexts, see #75 and need abapGit/abapGit#3607 to be merged