USe EcoreUtil.getAllContents() to display SCL tree as seen by EMF

Initiate CHANGELOG

See merge request !28

Resolve "Verification of enumerations against NSD are not right"

Closes #23

See merge request !27

Merge branch '29-allow-the-use-of-environment-variables-in-addition-to-command-line-options' into 'master'

Resolve "allow the use of environment variables in addition to command line options"

Closes #29

See merge request !25

Merge branch '28-the-base-lnclass-is-handled-differently-according-to-presence-conditions' into 'master'

Resolve "the base LNClass is handled differently according to presence conditions"

Closes #28

See merge request !24

Merge branch '27-take-into-account-prefixes-of-ocl-messages-to-classify-them-as-error-or-warning' into 'master'

Resolve "take into account prefixes of OCL messages to classify them as error or warning"

Closes #27

See merge request !23

Merge branch '22-enumtype-must-not-use-a-different-id-if-it-is-identical-to-the-nsd-one' into 'master'

Resolve "EnumType must not use a different id if it is identical to the NSD one"

Closes #22

See merge request !22

Error if EnumType id is not the same as NSD Enumeration name when it
should (same literals)

Resolve "update to EPL 2.0"

Closes #21

See merge request !21

Resolve "Add some information in README before mirroring on GitHub"

Closes #20

See merge request !20

Resolve "update to move to new gitlab server and new repository name"

Closes #19

See merge request !19

Resolve "static attributes prevent more than one validation"

Closes #18

See merge request RiseClipseGroup/RiseClipseValidator_SCL2003!18

Merge branch '17-if-output-is-the-last-option-the-output-file-is-also-considered-as-an-scl-file' into 'master'

Resolve "if --output is the last option, the output file is also considered as an SCL file"

Closes #17

See merge request RiseClipseGroup/RiseClipseValidator_SCL2003!17

Resolve "give option to output messages in a file"

Closes #16

See merge request RiseClipseGroup/RiseClipseValidator_SCL2003!16