v2.2.0 - yyyy-mm-dd

Changes affecting backward compatibility

-d:nimStrictDelete becomes the default. An index error is produced when the index passed to system.delete was out of bounds. Use -d:nimAuditDelete to mimic the old behavior for backwards compatibility.
The default user-agent in std/httpclient has been changed to Nim-httpclient/<version> instead of Nim httpclient/<version> which was incorrect according to the HTTP spec.
Methods now support implementations based on a VTable by using --experimental:vtables. Methods are then confined to be in the same module where their type has been defined.
With -d:nimPreviewNonVarDestructor, non-var destructors become the default.

Changed std/osfiles.copyFile to allow to specify bufferSize instead of a hardcoded one.
Changed std/osfiles.copyFile to use POSIX_FADV_SEQUENTIAL hints for kernel-level aggressive sequential read-aheads.
std/htmlparser has been moved to a nimble package, use nimble or atlas to install it.

Added newStringUninit to system, which creates a new string of length len like newString but with uninitialized content.
Added setLenUninit to system, which doesn't initalize slots when enlarging a sequence.
Added hasDefaultValue to std/typetraits to check if a type has a valid default value.
Added Viewport API for the JavaScript targets in the dom module.

noInit can be used in types and fields to disable member initializers in the C++ backend.
C++ custom constructors initializers see https://nim-lang.org/docs/manual_experimental.htm#constructor-initializer
member can be used to attach a procedure to a C++ type.
C++ constructor now reuses result instead creating this.

--nimcache using a relative path as the argument in a config file is now relative to the config file instead of the current directory.

koch now allows bootstrapping with -d:nimHasLibFFI, replacing the older option of building the compiler directly w/ the libffi nimble package in tow.