bidi control chars (RLE/LRE ... PDF) mapping out

[Soobok Lee]

If you have interests in IMA MUA display convention issues,
You can read attached examples.

Bidi Unicode identifiers can interfere with other 
unicode identifiers in the same display context and 
produce distorted display and may cause some kind of
security problems.

So, LRE...PDF sequences may be useful in the future
in various places where unicode identifiers are used.

That is why here I request experts' attention
to more "generous" treatment of LRE/RLE PDF 
rather than "just prohibit!" .

(again, UPPERCASED is RtoL char)
------
       eg1) 
        (network order)
           LCL123 at DOMAIN.tld
        
        (display order)
           NIAMOD at 123LCL.tld
        
        (display order after locapart in hex notation)
           %uXXXX%uXXXX%uXXXX123 at NIAMOD.tld
        
        eg2)
        (network order)
           ABCdefGHI at DOMAIN.tld
        
        (display order)
           CBAdefNIAMOD at IHG.tld
        
        (display order after locapart in hex notation)
           %uXXX...def%uXXXX... at NIAMOD.tld

        eg3)
        (network order)
           ABC at DOMAINlatin.TLD
        
        (display order)
           NIAMOD at CBAlatin.DLT
        
        (display order after locapart in hex notation)
           %uXXXX... at NIAMODlatin.DLT

------
   eg1) 
        (network order)
           local1 at DOMAIN1.TLD, LOCAL2 at domain2.tld
        
        (display order : distorted)
           local1 at 2LACOL ,DLT.1NIAMOD at domain2.tld

        (display order after replacement  of , ==> <LRM>, )
           local1 at DLT.1NIAMOD, 2LACOL at domain2.tld

        (display order after locapart in hex notation)
           local1 at DLT.1NIAMOD, %uXXXX... at domain2.tld
        
        eg2) 
        (network order)
           LOCAL1 at DOMAIN1.TLD, LOCAL2 at domain2.tld
        
        (display order : distorted)
           2LACOL, DLT.1NIAMOD at 1LACOL@domain2.tld

        (display order after replacement  of , ==> <LRM>, )
           DLT.1NIMOD at 1LACOL, 2LACOL at domain2.tld

        (display order after locapart in hex notation)
           DLT.1NIMOD at 1LACOL, %uXXXX... at domain2.tld

        eg3) 
        (network order)
           local1 at DOMAIN1.TLD, LOCAL2 at DOMAIN2.TLD
        
        (display order : distorted)
           local1 at DLT.2NIAMOD@2LACOL ,DLT.1NIAMOD

        (display order after replacement  of , ==> <LRM>, )
           local1 at DLT.1NIAMOD, DLT.2NIAMOD at 2LACOL

        (display order after hostname in punycode)
           local1 at xn--domain1.xn--tld1, LOCAL2 at DOMAIN2.TLD