Fix build warnings from editing and building.

[langfr]

Change pom.xml files to get rid of warnings when editing them in Eclipse and running maven install.

From Eclipse:

Description	Resource	Path	Location	Type
Invalid plugin configuration: encoding	pom.xml	/core	line 95	Language Servers

Description	Resource	Path	Location	Type
GroupId is duplicate of parent groupId	pom.xml	/library	line 11	Language Servers
Invalid plugin configuration: descriptorRefs	pom.xml	/library	line 173	Language Servers
Version is duplicate of parent version	pom.xml	/library	line 13	Language Servers

Description	Resource	Path	Location	Type
GroupId is duplicate of parent groupId	pom.xml	/validator	line 9	Language Servers
Invalid plugin configuration: descriptorRefs	pom.xml	/validator	line 137	Language Servers
Version is duplicate of parent version	pom.xml	/validator	line 14	Language Servers

Description	Resource	Path	Location	Type
GroupId is duplicate of parent groupId	pom.xml	/Mustang-CLI	line 10	Language Servers
Invalid plugin configuration: archive	pom.xml	/Mustang-CLI	line 114	Language Servers
Invalid plugin configuration: descriptorRefs	pom.xml	/Mustang-CLI	line 120	Language Servers
Version is duplicate of parent version	pom.xml	/Mustang-CLI	line 16	Language Servers

$ mvn clean install

[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.mustangproject:library:jar:2.12.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-surefire-plugin is missing. @ line 161, column 21
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.mustangproject:validator:jar:2.12.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-surefire-plugin is missing. @ line 108, column 21
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.mustangproject:Mustang-CLI:jar:2.12.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-surefire-plugin is missing. @ line 87, column 21
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.mustangproject:core:pom:2.12.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-surefire-plugin is missing. @ line 82, column 21
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.

[WARNING]  Parameter 'compilerVersion' (user property 'maven.compiler.compilerVersion') is deprecated: This parameter is no longer evaluated by the underlying compilers, instead the actual version of the javac binary is automatically retrieved.

[INFO] No artifact matching filter log4j:log4j
[INFO] No artifact matching filter com.sun.xml.bind:jaxb-impl