Introduces description mechanism.
Aliphatic chain description half done.
Fixed xpath expressions.
Merge branch 'master' into sre-description

Conflicts:
	src/main/java/io/github/egonw/CMLEnricher.java
	src/main/java/io/github/egonw/RichAtomSet.java
Merge branch 'master' into sre-description
Merge branch 'master' into sre-description
Merge branch 'master' into sre-description

Conflicts:
	src/main/java/io/github/egonw/CMLEnricher.java
High level aliphatic chain description.
Addedd Atom tables.
Pulls bond description into a separate function.
Merge branch 'master' into sre-description

Conflicts:
	src/main/java/io/github/egonw/CMLEnricher.java
Merge branch 'master' into sre-description

Conflicts:
	src/main/java/io/github/egonw/CMLEnricher.java
Adds atomic descriptions.
Adds description of connections.
Merge branch 'master' into sre-description
Merge branch 'master' into sre-description

Conflicts:
	src/main/java/io/github/egonw/CMLEnricher.java
Merge branch 'master' into sre-description
Merge branch 'master' into sre-description
Sorting out type changes.
Makes description robust against missing positions.