Tidy up decode-related headers (#280)

Check and reduce some dependency between decode headers

Rename qcbor_decode to qcbor_main_decode to be more clear and help with header backwards compatibility 

Fix a header include backwards compatibility to v1 issue

Fix long lines and trailing spaces


Co-authored-by: Laurence Lundblade <lgl@securitytheory.com>
diff --git a/inc/qcbor/UsefulBuf.h b/inc/qcbor/UsefulBuf.h
index 1ed558b..80b5c78 100644
--- a/inc/qcbor/UsefulBuf.h
+++ b/inc/qcbor/UsefulBuf.h
@@ -1471,7 +1471,7 @@
  *
  * @return  0 for equality, positive if uStart1 is lexographically larger,
  *          negative if uStart2 is lexographically larger.
- * 
+ *
  * This looks into bytes that have been output at the offsets @c start1
  * and @c start2. It compares bytes at those two starting points until
  * they are not equal or @c uLen1 or @c uLen2 is reached. If the
@@ -1894,7 +1894,7 @@
  * @param[in] uLen2     Length of second range of bytes.
  *
  * This returns the same as UsefulBuf_Compare().
- * 
+ *
  * If the offset or the length plus offset or a range extends outside
  * the input buffer, that range of bytes will be considered greater
  * than the other string. If both are outside this is considered a