Introduce pause mechanics, refactor a little

Introduce Pause mechanics and mention it in README.md.
Makefile: replace unnecessary "-MMD -MP" with just "-MD" flag, so it
allows to compile with tcc too.
Refactor: Rename game.isStarted field to game.started field. Move
arrKeys container to engine.c and remove it from main.c. Refactor char
iterator in utf8to32_strcpy function.

1 files changed, 2 insertions, 1 deletions

diff --git a/include/common.h b/include/common.h
index ca2e499..3273c66 100644
--- a/include/common.h
+++ b/include/common.h
@@ -1,6 +1,7 @@
 struct game {
     unsigned int level;
-    int          isStarted;
+    int          started;
+    int          paused;
     int          scoreCurrent;
     int          moveLatency;
     int          lines;