Generate #defines for initializing message structures.

Usage like:
MyMessage foo = MyMessage_init_default;

MyMessage_init_default will initialize to default values defined in .proto.

MyMessage_init_zero will initialize to null/zero values. Same results as {}
or {0}, but will avoid compiler warnings by initializing everything explicitly.

Update issue 79
Status: FixedInGit

Make all the tests ANSI C compatible.

Start moving the tests into subfolders. Transition to SCons for build system for the tests.

Only a few tests updated so far. Have to include all the rest before merging to mainline.

Update issue 63
Status: Started