Add configuration for Ninja build system

Run configure.py to generate a build.ninja file to build with ninja.

$ ./configure.py
$ ninja

Ninja can also build individual targets, for example

$ ninja bin/libflatland.so
$ ninja bin/test/test1

1 files changed, 23 insertions, 0 deletions

diff --git a/ninja/rules.ninja b/ninja/rules.ninja
new file mode 100644
index 0000000..2a56923
--- /dev/null
+++ b/ninja/rules.ninja
@@ -0,0 +1,23 @@
+includes = -I engine/include
+cflags = -Wall -pedantic -fPIC -std=c++17 $includes
+
+libs = 
+lflags = -lSDL2 $libs
+
+flags = -fdiagnostics-color
+
+rule mkdir
+    command = mkdir -p $out
+    description = creating directory $out
+
+rule cpp
+    command = g++ $flags $cflags -c $in -o $out $lflags
+    description = compiling $in
+
+rule link
+    command = g++ $flags $cflags -o $out $in $lflags
+    description = linking $out
+
+rule link-shared
+    command = g++ $flags $cflags -shared -o $out $in $lflags
+    description = linking $out