New features

#1092 - @ivanstus built a validation plugin for Amazon Route53, which now comes bundled with the release in a separate download.

Enhancements

#1089 - Some more information about the renewal is included in success and failure notification emails, to make it easier to identify which certificate the message is about and what went wrong, requested by @Virinum
#1091 - More information is logged to the screen during the DNS pre-validation to allow easier debugging, thanks to @ericcan
#1102 - If you have the same host name set up on different IIS web sites (i.e. with different ports), both of them will be selectable by the IISBinding plugin. Also non-default port numbers will be shown in the list to make them easier to distinguish. Requested by @danielgindi
Change execution policy for .ps1 scripts from RemoteSigned to ByPass, because our example script will generally be marked as "remote" for being downloaded from the internet.
Add repeatable pre-validation to the Manual DNS validation plugin, so that you'll be less likely to run into incorrigible issues and have to start setting up the renewal all over because you made a small mistake.
Add general DNS pre-validation with a 2.5 minute time-out so that any DNS plugin (scripted or otherwise) will have less to worry about timing issues and more diagnostic information is available when problems arise.

#1062 - Depending on your Windows version and language (e.g. Server 2012 with Chinese and Japanse), the program would crash when trying to copy-paste text from the console window. Reported by @JohnsonWang1222 and with big help from @I-Otsuki
#1083 - Fix a bug related to different ways a binding with no specific IP address could be created. While the IIS manager consistently uses *, the Exchange installer creates <blank> bindings instead, which mistakenly allowed a duplicate binding to be created. Reported by @joeio.
#1093 - The Azure DNS plugin was broken due to a GUID collision bug created by the import function, found and fixed by @tylerszabo.
#1101 - Creating the scheduled task from the main menu would set up the old ACMEv1 endpoint instead of the ACMEv2 endpoint, reported by @Micrologiciel
#1103 - Importing renewals from 1.9.x that used TLS-SNI-01 validation will now be converted to SelfHosting instead of FileSystem validation. Also a warning will be shown that this type of validation has been removed from ACMEv2.
Prevent deletion attempts for files that haven't been created yet, to reduce superfluous error messages.