Fix nits in pod files.

Add doc-nit-check to help find future issues.
Make podchecker be almost clean.
Remove trailing whitespace.
Tab expansion

Reviewed-by: Richard Levitte <levitte@openssl.org>
diff --git a/doc/crypto/OBJ_nid2obj.pod b/doc/crypto/OBJ_nid2obj.pod
index a17ba7b..211c355 100644
--- a/doc/crypto/OBJ_nid2obj.pod
+++ b/doc/crypto/OBJ_nid2obj.pod
@@ -42,7 +42,7 @@
 The ASN1 object utility functions process ASN1_OBJECT structures which are
 a representation of the ASN1 OBJECT IDENTIFIER (OID) type.
 
-OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID B<n> to 
+OBJ_nid2obj(), OBJ_nid2ln() and OBJ_nid2sn() convert the NID B<n> to
 an ASN1_OBJECT structure, its long name and its short name respectively,
 or B<NULL> is an error occurred.
 
@@ -70,7 +70,7 @@
 
 OBJ_dup() returns a copy of B<o>.
 
-OBJ_create() adds a new object to the internal table. B<oid> is the 
+OBJ_create() adds a new object to the internal table. B<oid> is the
 numerical form of the object, B<sn> the short name and B<ln> the
 long name. A new NID is returned for the created object.
 
@@ -127,7 +127,7 @@
 Check if an object is B<commonName>
 
  if (OBJ_obj2nid(obj) == NID_commonName)
-	/* Do something */
+        /* Do something */
 
 Create a new NID and initialize an object from it:
 
@@ -136,14 +136,14 @@
  new_nid = OBJ_create("1.2.3.4", "NewOID", "New Object Identifier");
 
  obj = OBJ_nid2obj(new_nid);
- 
+
 Create a new object directly:
 
  obj = OBJ_txt2obj("1.2.3.4", 1);
 
 =head1 BUGS
 
-OBJ_obj2txt() is awkward and messy to use: it doesn't follow the 
+OBJ_obj2txt() is awkward and messy to use: it doesn't follow the
 convention of other OpenSSL functions where the buffer can be set
 to B<NULL> to determine the amount of data that should be written.
 Instead B<buf> must point to a valid buffer and B<buf_len> should