The core folder is now a symlink to a versioned folder

This will allow to work on different versions of core from
different branches without having to repeat the download
Move the bin symlink into the build folder

Removes clutter from the root folder
No need to remove the bin folder now
Move build.log into the build folder

Another effort to de-clutter the root folder
Upgrade to use core library version 0.80.3
Merge pull request #634 from realm/ez-build-log

Move build.log into the build folder
Merge branch 'master' into ez-buildbin

* master:
  There are a few implicit casts stopping master from successfully testing/building in Realm.xcodeproj
  changelog
  Using the Realm’s schema when validating relationship queries.
  Core does only support link queries in the for X.Y.
  add transaction block helper
  Safer string conversion
  ANY does also work
  A little style
  Cleaning up unit tests and adding more explaination to the changelog
  Support for querying objects' RLMArray properties
  Updating changelog
  Adding basic support link queries
  Version bump
  make property initializer private, update swift
  add JP's dynamic tests, fix for setting usig object subscripting on standalone objects
Merge pull request #640 from realm/ks-use-core-ver-0.80.3

Upgrade to use core library version 0.80.3
Merge branch 'master' into ez-buildbin

* master:
  Upgrade to use core library version 0.80.3
  Move build.log into the build folder
delete build/bin, otherwise the symlink will fail
Merge pull request #633 from realm/ez-buildbin

Move the bin symlink into the build folder
Merge branch 'master' into ez-core-symlink

* master:
  delete build/bin, otherwise the symlink will fail
  There are a few implicit casts stopping master from successfully testing/building in Realm.xcodeproj
  Upgrade to use core library version 0.80.3
  changelog
  Using the Realm’s schema when validating relationship queries.
  Core does only support link queries in the for X.Y.
  add transaction block helper
  Safer string conversion
  ANY does also work
  A little style
  Cleaning up unit tests and adding more explaination to the changelog
  Support for querying objects' RLMArray properties
  Updating changelog
  Adding basic support link queries
  Version bump
  Move build.log into the build folder
  No need to remove the bin folder now
  Move the bin symlink into the build folder
  make property initializer private, update swift
  add JP's dynamic tests, fix for setting usig object subscripting on standalone objects
Merge pull request #632 from realm/ez-core-symlink

The core folder is now a symlink to a versioned folder
Merge branch 'master' into ez-browser

* master:
  delete build/bin, otherwise the symlink will fail
  Upgrade to use core library version 0.80.3
  Move build.log into the build folder
  No need to remove the bin folder now
  Move the bin symlink into the build folder
  The core folder is now a symlink to a versioned folder