added C encoder

examples/simple_java/compile.sh

examples/simple_java/example_encoder.c

test/gen/c/nested.c

test/gen/c/nested.h

test/gen/c/simple.c

test/gen/c/simple.h

test/gen/csharp/nested.cs

test/gen/csharp/simple.cs

test/gen/csharp/test_nested.cs

test/gen/csharp/test_simple.cs

test/gen/java/nested/int_array_s.java

test/gen/java/nested/int_array_t_s.java

test/gen/java/nested/int_s.java

test/gen/java/nested/int_t_s.java

test/gen/java/nested/struct_array_s.java

test/gen/java/nested/struct_array_ss.java

test/gen/java/nested/struct_array_t.java

test/gen/java/nested/struct_array_t_s.java

test/gen/java/nested/struct_s.java

test/gen/java/nested/struct_struct_s.java