* fix failing test toSeq in manual which now works
* changelog
* reject proc fn(a: iterable)
* add iterable to spec
* remove MCS/UFCS limitation that now works
* fixes#15210 [backport:1.2]
* make tests green
* make ordinal work
* makes Swapable test compile
* make Indexable example work
* concepts: 'self' is now 'Self'
* concepts: make Dictionary example compile
* document the new concept implementation
* concepts: make typeDesc work properly
* concepts: allow documentation comments (d'oh)
Make `requiresInit` pragma to work for distinct types in addition to
objects. Tagging of distinct types with `requiresInit` pragma was
already supported, but its impact wasn't applied. Now its behavior when
applied on distinct types is as follows.
Given the following distinct type definitions:
```nim
type
DistinctObject {.requiresInit, borrow: `.`.} = distinct MyObject
DistinctString {.requiresInit.} = distinct string
```
The following code blocks will fail to compile:
```nim
var foo: DistinctFoo
foo.x = "test"
doAssert foo.x == "test"
```
```nim
var s: DistinctString
s = "test"
doAssert s == "test"
```
But these ones will compile successfully:
```nim
let foo = DistinctFoo(Foo(x: "test"))
doAssert foo.x == "test"
```
```nim
let s = "test"
doAssert s == "test"
```
* spec for view types
* spec additions
* refactoring; there are two different kinds of views
* refactorings and spec additions
* enforce that view types are initialized
* enforce borrowing from the first formal parameter
* enforce lifetimes for borrowing of locals
* typo in the manual
* clarify in the implementation what a borrow operation really is
* refactoring: move procs to typeallowed.nim
* frontend preparations for first class openArray support
* prepare the code generator for first class openArray
* code generation for first class openArray; WIP
* code generation for open arrays, progress
* added isViewType proc
* preparations for borrow checking
* added borrow checking to the front end
