Add LICENSE.md and clarify snippet from curl

Author: svedi

LICENSE

@@ -0,0 +1,74 @@
+The Cryptolens Client API for C++ is licensed under the 2-Clause BSD License
+given below. The client API consists of the files in the `examples/`, `include/`,
+`src/` and `vsprojects/` directories.
+
+```
+Copyright (c) 2019, Cryptolens AB
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+```
+
+## Dependencies
+
+The client API depends on other libraries for it to function correctly.
+
+Currently, all versions and configurations are set up to use the
+base64 implementation found in `third_party/base64_OpenBSD/`. This
+implementation is licensed under a ISC license as well as something
+similar to a 3-Clause BSD license, for more details, see the files in
+the directory.
+
+In the `master` branch on Github we have for conveniance included several
+other dependencies in the `third_party/` directory. Which of these are used
+depends on how the `basic_Cryptolens` or `basic_SKM` class is set up, as well
+as how you set up your build environment.
+
+The following sections cover which dependencies from `third_party/` are
+included by default for the different api versions.
+
+### Core dependencies
+
+This section details the dependencies which are used independently of which
+template arguments are provided to the `basic_Cryptolens` or `basic_SKM`
+class. 
+
+More precisly, the following dependencies are included when using the
+`cryptolens_io::v20180502` namespace, or when using the
+`cryptolens_io::v20190401` namespace with `Configuration_Unix`,
+`Configuration_Unix_IgnoreExpires`, `Configuration_Windows` or
+`Configuration_Windows_IgnoreExpires` as the `Configuration` template
+argument to `basic_Cryptolens` class.
+
+ * [ArduinoJson 5](https://github.com/bblanchon/ArduinoJson) from the
+   `third_party/ArduinoJson` directory.
+ * [optional lite](https://github.com/martinmoene/optional-lite) from
+   the `third_party/optional-lite` is used when compiling against
+   C++-14 or below.
+
+### Configuration dependent dependencies
+
+When using `Configuration_Windows`, `Configuration_Windows_IgnoreExpires`
+or `RequestHandler_WinHTTP` the default build configurations link against
+the code in `third_party/curl`. This code consists of a single, very simple
+function from the [cURL](https://curl.haxx.se/) library. It is unclear
+to us if this function is complex enough to be covered by copyright.

LICENSE.md

@@ -157,30 +157,6 @@ RequestHandler_WinHTTP_PostBuilder::make(basic_Error & e)
 
 namespace internal {
 
-/* FROM CURL */
-static bool Curl_isunreserved(unsigned char in)
-{
-  switch (in) {
-    case '0': case '1': case '2': case '3': case '4':
-    case '5': case '6': case '7': case '8': case '9':
-    case 'a': case 'b': case 'c': case 'd': case 'e':
-    case 'f': case 'g': case 'h': case 'i': case 'j':
-    case 'k': case 'l': case 'm': case 'n': case 'o':
-    case 'p': case 'q': case 'r': case 's': case 't':
-    case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
-    case 'A': case 'B': case 'C': case 'D': case 'E':
-    case 'F': case 'G': case 'H': case 'I': case 'J':
-    case 'K': case 'L': case 'M': case 'N': case 'O':
-    case 'P': case 'Q': case 'R': case 'S': case 'T':
-    case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
-    case '-': case '.': case '_': case '~':
-      return 1;
-    default:
-      break;
-  }
-  return 0;
-}
-
 std::string
 percent_encode(std::string const& s)
 {