default values should be present for missing values

Resolve "DataAttribute may refer to ConstructedAttribute or to Enumeration"

Closes #22

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!21

move links to BasicType/ConstructedAttribute/Enumeration from
DataAttribute to AgAttribuuteType and add code for creating links
SubDataAttribute

Resolve "provide stream for other NSD objects"

Closes #21

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!20

Resolve "prefix messages about resolving links"

Closes #20

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!19

Resolve "update to resource changes in Main"

Closes #19

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!18

Resolve "update to changes in Main"

Closes #18

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!17

Resolve "provide links to NSDoc elements when they are present"

Closes #17

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!16

Resolve "use Parent prefix for inverse containment links (like SCL)"

Closes #16

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!15

Resolve "Models loaders should be with their metamodels"

Closes #15

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!14

Resolve "add initial GitLab CI configuration"

Closes #14

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!13

Resolve "add pom.xml files"

Closes #13

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2016!12

Merge branch '9-add-needed-stuff-to-allow-for-loading-nsd-files-with-riseclipseeditor' into 'master'

Resolve "add needed stuff to allow for loading NSD files with RiseClipseEditor"

Closes #9

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2017!8

Resolve "add needed services in NsdResourceSet"

Closes #7

See merge request RiseClipseGroup/RiseClipseMetamodel_NSD2017!6

# Conflicts:
#   fr.centralesupelec.edf.riseclipse.iec61850.nsd/src/fr/centralesupelec/edf/riseclipse/iec61850/nsd/impl/BasicTypeImpl.java
#   fr.centralesupelec.edf.riseclipse.iec61850.nsd/src/fr/centralesupelec/edf/riseclipse/iec61850/nsd/impl/NSImpl.java