added links to @dmhowcroft's introductory posts

Also did some formatting cleanup

Duplicate subexpression in Slash.java

`_ability == ACTIVE` is repeated.

Added option to allow categories with missing index nominals on their target cats to combine during realization, as an exception to the index filter, so that type-raised cats involving sibling dependencies can combine prior to combining with the head cat.

Remove warnings (unclosed readers/writers and unsafe varargs)

Changed handling of ccgbank/extract to ignore all files (with exceptions) rather than the whole directory itself.

Added note re lack of guarantee of lex lookup returning the right arg roles if word-cat pair is observed.

Turned off use of norm_blue in n-best output, adding -nbestnormbleu switch to turn it back on if desired.