This patch clarifies some of the coding choices with documentationa and
removes a limitation in the code for future expansion of the CHAR and
BINARY fields to length > 255.


sql/field.cc:
  BUG#30790 : Suspicious code in rpl_utility.cc
  
  This patch adds an assertion to ensure we are not attempting to encode
  negative values.
sql/log_event.cc:
  BUG#30790 : Suspicious code in rpl_utility.cc
  
  This patch adds comments to help explain the choice of variable types.
sql/rpl_utility.cc:
  BUG#30790 : Suspicious code in rpl_utility.cc
  
  This patch removes code from the calc_field_size that is not needed and
  was ambiguous. Originally intended to future expansion, the code was
  not needed.
  
  Also added are comments to help explain some portions of the code.
  
  A change was made to the korr method to use the unsigned version to 
  avoid extended sign problems.
sql/rpl_utility.h:
  BUG#30790 : Suspicious code in rpl_utility.cc
  
  This patch corrects some type discrepencies and removes an extra cast.