Compile cppformat and include it in the Cantera library

.gitignore

@@ -8,6 +8,7 @@
 build/
 test/work/
 include/cantera/base/config.h
+include/cantera/ext/
 interfaces/matlab/ctpath.m
 interfaces/matlab/Contents.m
 stage/

ext/SConscript

@@ -47,9 +47,17 @@ def prep_gtest(env):
                     CPPDEFINES={'GTEST_HAS_PTHREAD': 0})
     return localenv
 
+def prep_cppformat(env):
+    localenv = prep_default(env)
+    build(localenv.Command("#include/cantera/ext/format.h",
+                           "#ext/cppformat/format.h",
+                           [Mkdir("#include/cantera/ext"),
+                            Copy('$TARGET', '$SOURCE')]))
+    return localenv
 
 # each element of libs is: (subdir, (file extensions), prepfunction)
-libs = [('libexecstream', ['cpp'], prep_default)]
+libs = [('libexecstream', ['cpp'], prep_default),
+        ('cppformat', ['cc'], prep_cppformat)]
 
 if env['build_with_f2c']:
     libs.append(('f2c_math', ['cpp','c'], prep_f2c))