- various engine updates from Raze.

* removed refreshFreq variable and related code. This only got into the backend because of stupid interpolation code in some of the Build games which has long been removed.
* save FixedBitArrays as base64 in savegames.
* allow indirections in the string table - by prefixing the language string with '$$' the remaining text is interpreted as another string label to resolve.
* constexpr in palette code, also replacing #defines with enums.

src/common/thirdparty/base64.cpp

@@ -0,0 +1,139 @@
+/* 
+   base64.cpp and base64.h
+
+   base64 encoding and decoding with C++.
+
+   Version: 1.01.00
+
+   Copyright (C) 2004-2017 René Nyffenegger
+   Copyright (C) 2020 Christoph Oelckers
+
+   This source code is provided 'as-is', without any express or implied
+   warranty. In no event will the author be held liable for any damages
+   arising from the use of this software.
+
+   Permission is granted to anyone to use this software for any purpose,
+   including commercial applications, and to alter it and redistribute it
+   freely, subject to the following restrictions:
+
+   1. The origin of this source code must not be misrepresented; you must not
+      claim that you wrote the original source code. If you use this source code
+      in a product, an acknowledgment in the product documentation would be
+      appreciated but is not required.
+
+   2. Altered source versions must be plainly marked as such, and must not be
+      misrepresented as being the original source code.
+
+   3. This notice may not be removed or altered from any source distribution.
+
+   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
+
+   Addapted by Christoph Oelckers to FSerializer's needs where std::string is not a good container.
+
+*/
+#include <stdint.h>
+#include "base64.h"
+
+static const char *base64_chars = 
+             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+             "abcdefghijklmnopqrstuvwxyz"
+             "0123456789+/";
+
+inline int base64toindex(int c)
+{
+    if (c >= 'A' && c <= 'Z') return c - 'A';
+    if (c >= 'a' && c <= 'z') return c - 'a' + 26;
+    if (c >= '0' && c <= '9') return c - '0' + 52;
+    if (c == '+') return 62;
+    if (c == '/') return 63;
+    return -1;
+}
+
+static inline bool is_base64(unsigned char c) {
+    return base64toindex(c) >= 0;
+}
+
+TArray<uint8_t> base64_encode(unsigned char const* bytes_to_encode, size_t in_len) {
+  TArray<uint8_t> reta((in_len+5)/6 + 6);
+  int i = 0;
+  int j = 0;
+  unsigned char char_array_3[3];
+  unsigned char char_array_4[4];
+
+  while (in_len--) {
+    char_array_3[i++] = *(bytes_to_encode++);
+    if (i == 3) {
+      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
+      char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
+      char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
+      char_array_4[3] = char_array_3[2] & 0x3f;
+
+      for(i = 0; (i <4) ; i++)
+        reta.Push(base64_chars[char_array_4[i]]);
+      i = 0;
+    }
+  }
+
+  if (i)
+  {
+    for(j = i; j < 3; j++)
+      char_array_3[j] = '\0';
+
+    char_array_4[0] = ( char_array_3[0] & 0xfc) >> 2;
+    char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
+    char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
+
+    for (j = 0; (j < i + 1); j++)
+      reta.Push(base64_chars[char_array_4[j]]);
+
+    while((i++ < 3))
+      reta.Push('=');
+
+    reta.Push(0);
+  }
+
+  return reta;
+
+}
+
+void base64_decode(void *memory, size_t maxlen, const char *encoded_string) {
+    size_t in_len = strlen(encoded_string);
+    int i = 0;
+    int j = 0;
+    int in_ = 0;
+    unsigned char char_array_4[4], char_array_3[3];
+    uint8_t* dest = (uint8_t*)memory;
+    uint8_t* end = dest + maxlen;
+
+    while (in_len-- && (encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
+        char_array_4[i++] = encoded_string[in_]; in_++;
+        if (i == 4) {
+            for (i = 0; i < 4; i++)
+                char_array_4[i] = base64toindex(char_array_4[i]) & 0xff;
+
+            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
+            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
+            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
+
+            for (i = 0; (i < 3); i++)
+                *dest++ = char_array_3[i];
+            if (dest >= end) return;
+            i = 0;
+        }
+    }
+
+    if (i) {
+        for (j = 0; j < i; j++)
+            char_array_4[j] = base64toindex(char_array_4[j]) & 0xff;
+
+        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
+        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
+
+        for (j = 0; (j < i - 1); j++)
+        {
+            *dest++ = char_array_3[j];
+            if (dest >= end) return;
+        }
+    }
+    while (dest < end) *dest++ = 0;
+}