Simplify code for CSubnet

Simplify the code by using CAddress.ip directly, instead of the reversed
GetByte() semantics.

src/netbase.cpp

@@ -1252,12 +1252,12 @@ CSubNet::CSubNet(const std::string &strSubnet, bool fAllowLookup)
             std::string strNetmask = strSubnet.substr(slash + 1);
             int32_t n;
             // IPv4 addresses start at offset 12, and first 12 bytes must match, so just offset n
-            int noffset = network.IsIPv4() ? (12 * 8) : 0;
+            const int astartofs = network.IsIPv4() ? 12 : 0;
             if (ParseInt32(strNetmask, &n)) // If valid number, assume /24 symtex
             {
-                if(n >= 0 && n <= (128 - noffset)) // Only valid if in range of bits of address
+                if(n >= 0 && n <= (128 - astartofs*8)) // Only valid if in range of bits of address
                 {
-                    n += noffset;
+                    n += astartofs*8;
                     // Clear bits [n..127]
                     for (; n < 128; ++n)
                         netmask[n>>3] &= ~(1<<(n&7));
@@ -1271,12 +1271,10 @@ CSubNet::CSubNet(const std::string &strSubnet, bool fAllowLookup)
             {
                 if (LookupHost(strNetmask.c_str(), vIP, 1, false)) // Never allow lookup for netmask
                 {
-                    // Remember: GetByte returns bytes in reversed order
                     // Copy only the *last* four bytes in case of IPv4, the rest of the mask should stay 1's as
                     // we don't want pchIPv4 to be part of the mask.
-                    int asize = network.IsIPv4() ? 4 : 16;
-                    for(int x=0; x<asize; ++x)
-                        netmask[15-x] = vIP[0].GetByte(x);
+                    for(int x=astartofs; x<16; ++x)
+                        netmask[x] = vIP[0].ip[x];
                 }
                 else
                 {
@@ -1296,7 +1294,7 @@ bool CSubNet::Match(const CNetAddr &addr) const
     if (!valid || !addr.IsValid())
         return false;
     for(int x=0; x<16; ++x)
-        if ((addr.GetByte(x) & netmask[15-x]) != network.GetByte(x))
+        if ((addr.ip[x] & netmask[x]) != network.ip[x])
             return false;
     return true;
 }

src/netbase.h

@@ -100,6 +100,8 @@ class CNetAddr
         inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
             READWRITE(FLATDATA(ip));
         }
+
+        friend class CSubNet;
 };
 
 class CSubNet