Increased needed memory for APC to 512M + code cleanup

- Increased the needed memory for APC to 512M as we often run into memory problems on our 256M box
- fixed the RAM calculation to divide by 1024 and not 1000
- code cleanup (renaming variables and creating new to avoid magic numbers)
touch up text, s/nat/NAT/
add option to send prefix hint for requesting desired prefix length for delegation

This change adds an option on the interfaces page for sending a prefix hint for the selected delegation size. If enabled, a "prefix" field requesting :: with the appropriate prefix length (64 - dhcp6-ia-pd-len) is added to the "id-assoc pd" entry in the dhcp6c config file. This hint is required for requesting prefixes shorter than /64 from Comcast.
fix text
Resolves #3177. Do a filter reconfigure if the dynds ipsec hosts are present and being reloaded.
Traffic Shaper GUI text typos

and note the Queue Limit is a number of packets (not packets per second)
Make sure RRD data is restored from backup before upgrading data and a new backup is done after. It should fix #2159
Fix issue reported on http://forum.pfsense.org/index.php/topic,66160.0.html
Fix #3004:

. Create a function to replace strings on deep associative arrays
. Use the recent created function array_replace_values_recursive to fix
  VIP interface names instead of touch config.xml directly
Correct typo on variable name
Disable state killing on gateway failure by default for new configs.
Clarify the text describing the option while here.
Bring back static routes to fix issues reported on Ticext #3179
Merge pull request #793 from shahidsheikh/master

Fix #3174 Handling of gateway groups in openvpn_restart()
Merge pull request #796 from phil-davis/master

Traffic Shaper GUI text typos
Merge pull request #786 from individual-it/master

Increased needed memory for APC to 512M + code cleanup
Remove SPD when disable phase2, it fixes #2719
Fixes #3173 if any port information exists on the rule than put it on the NEGATE rule generated.
filter_generate_port error log function name

Absolutely minor adjustment to make the error log message refer to the new function name.
Merge pull request #797 from phil-davis/master

filter_generate_port error log function name
Sprinkle some unsets to reduce footprint and correct some whitespaces