Minor style cleanups from PMD. I'm ignoring the if(!blah)-is-bad one though.
Improve l10n for config options for cache.
Centralise memory limit detection hacks. Also make logic using it slightly more cautious in some places.
Reinstate 400 thread limit for 256MB.
Fix limiting to integer.max (cast in wrong place)
Merge commit 'b78e124af19e06a5d856ac79eb833482f93755b2' into delayed-writes
Improve l10n
Only cache if the key could fit in the memory limit. Pass through if e.g. the limit is set big enough for one kind of key but not another.
Make default cache size depend on memory limit.
Check cache size on startup.
Improve config docs, split into config and config long like most configs.
Only create CachingFreenetStore object if cache size is > 0
Add test for very small cache size.
Get rid of ancient back compat code.
Merge branch 'next' into delayed-writes

Conflicts:
	src/freenet/node/NodeClientCore.java
Merge branch 'next' into centralise-memory-limit-hacks

Conflicts:
	src/freenet/node/NodeClientCore.java
Fix logging string re memory
Expand the datastore size calculation to make it more obvious what we are doing.
Explain (comments)
Allow 50% of available memory for slot filters, not 80%.