All errors that lead to MTP request resending by default
error handler now can be handled differently. For example
inline bot requests are not being resent on 5XX error codes.
+ extensive use of auto keyword in MTP types handling.
for inline and external bot keyboard handling.
But it needs to reinvent a good improvement/replacement
for ITextLink concept that will support automatic calls
of linkOver()/linkOut() methods in all link holders.
