[#2144] Improve AbstractField.equals() and AbstractTable.equals()
and similar, as these two are called very often

Conflicts:
	jOOQ/src/main/java/org/jooq/impl/AbstractRecord.java
	jOOQ/src/main/java/org/jooq/impl/TableFieldImpl.java
[#2144] Improve AbstractField.equals() and AbstractTable.equals() -
null-safe equals() checks

Conflicts:
	jOOQ/src/main/java/org/jooq/impl/AbstractField.java
	jOOQ/src/main/java/org/jooq/impl/AbstractTable.java