-Add a few miscellaneous functions needed by the networking subsystem:
-Net_Log2 to return the integer log base 2 of a number
-Net_BitsNeeded to return the minimum number of bits needed to store a number
-Net_CRC32 to calculate the 32bit CRC of a buffer.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4121 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add default hashing functors for string types.
-Fix compilation issues with HashTable::const_iterator.
-Clean up the code a bit.

git-svn-id: http://odamex.net/svn/root/branches/net3-base@4122 b0bcef46-2027-0410-bd56-ab726e9a1d04