Spelling fixes.

BUGS.txt

@@ -54,7 +54,7 @@ So, if your program doesn't compile, tell me so, tell me where the
 error occurs, and include a complete Perfectly Valid Test Program(tm).
 You tell me that it fails to compile for you, and I find that it
 compiles for me, then hooray I fixed it. It can happen, you
-know. What's on my disk is more recent then the latest snapshot.
+know. What's on my disk is more recent than the latest snapshot.
 
 If your program does compile, but generates incorrect output, I need
 to know what it says and what you think it should say. From this I can

elab_expr.cc

@@ -967,7 +967,7 @@ unsigned PEBLogic::test_width(Design*des, NetScope*scope,
 }
 
 NetExpr*PEBLogic::elaborate_expr(Design*des, NetScope*scope,
-				 int expr_width_dummp, bool sys_task_arg) const
+				 int expr_width_dummy, bool sys_task_arg) const
 {
       assert(left_);
       assert(right_);

net_design.cc

@@ -294,7 +294,7 @@ void NetScope::run_defparams_later(Design*des)
 	    (*cur)->evaluate_parameters(des);
 
 	// If there are some scopes that still have missing scopes,
-	// then sav them back into the defparams_later list for a
+	// then save them back into the defparams_later list for a
 	// later pass.
       defparams_later = defparams_even_later;
       if (! defparams_later.empty())

vvp/vvp_net.cc

@@ -36,7 +36,7 @@
 # include "sfunc.h"
 #endif
 
-// Allocate around 1Megbytes/chunk.
+// Allocate around 1Megabytes/chunk.
 static const size_t VVP_NET_CHUNK = 1024*1024/sizeof(vvp_net_t);
 static vvp_net_t*vvp_net_alloc_table = 0;
 #ifdef CHECK_WITH_VALGRIND