remove outdated vcxproj files add basic build instructions

ChangeLog.txt

@@ -2,6 +2,7 @@ List of Changes since the Fork
 ==============================
 In reverse chronological order:
 
+- remove long outdated vcxproj files, support building with cmake and nmake only on Windows
 - change update foreign attributes to remove xml:base and add xlink:arcrole to follow whatwg spec
 - fixed minor memory leaks
 - correctly handle text in form elements

README.md

@@ -39,7 +39,7 @@ Original Goals & features:
 Installation
 ============
 
-To build and install the library, use CMake version 3.0 or later
+To build and install the library on macOS and Linux/Unix, use CMake version 3.0 or later
 
     git clone https://github.com/Sigil-Ebook/sigil-gumbo.git
     mkdir build
@@ -48,6 +48,21 @@ To build and install the library, use CMake version 3.0 or later
     make -j4
 
 
+To build the library on Windows, use CMake version 3.0 or later
+
+   1. clone the sigil gumbo repo
+   git clone https://github.com/Sigil-Ebook/sigil-gumbo.git
+
+   2. create a seprate build directory (do not build in the source directory itself)
+   mkdir build
+   cd build
+
+   3. Start the Visual Studio Command prompt for x64
+
+   4. cmake -G "NMake Makefiles" ..\sigil-gumbo
+      nmake
+
+
 To run the html5lib tree-construction test suite from the build directory
 after building