fix Issue 10094 - NRVO with static array return should work
Fix bug 10275 CTFE: allow const casts of struct literals

This was permitted in const-folding, but not in CTFE until now.
Allow NullExp as struct hidden member in struct literals

Since CTFE will create null hidden pointers.
Fix bug 10217 ICE(root.c) with nested struct.init.tupleof in CTFE

CTFE version of bug 9315, almost exactly the same fix.
If a nested struct has no initialized hidden pointer, set it to null
to match the runtime behaviour.
fix Issue 10249 - incorrect mangling for overloaded symbol
Get rid of #ifs for dylib and fPIC switches
fix Issue 10373 - cannot resolve forward reference
fix Issue 10375 - private template from imported module hijacks a template type parameter(!)
improve hash speed
convert template lookup to hash table
Move Signalling NaN value into Port.
Merge pull request #2250 from ibuclaw/portsnan

Move Signalling NaN value into Port.
Merge pull request #2178 from yebblies/dylib

[DDMD] Make dylib a warning and fix #ifs
use unsigned value for interface offset
speed up based on gprof data
Merge pull request #2192 from 9rnsr/fix10373

[REG2.063] Issue 10373 - cannot resolve forward reference
Merge pull request #2252 from dawgfoto/fix10457

use unsigned value for interface offset
Merge pull request #2239 from WalterBright/hash_instance

convert template lookup from array to hash table
Merge pull request #2248 from WalterBright/tweak-hash

tweak rehash threshhold
Merge pull request #2247 from WalterBright/speed_up_search

speed up based on gprof data