* Added support for file types across platforms (#26)

* Added support for file types across platforms

- Added per platform file type support, so you can specify what kind of files you want the picker to support
- Updated iOS's picker to use the non-deprecated `UIDocumentPickerViewController`
- Minor tweaks, such as package updates

* Fixed an issue with the iOS implementation, where the returned path wasn't properly formatted/absolute, which in turn meant that the path wasn't valid as is.

* A few iOS specific improvements

* Get latest changes to master (#51)

* pull master into develop before merging back (#47)

* Resolved issues with referencing from NuGet package (#29)

Simplified the nuspec file to work with wildcards and fixed macOS assembly name.
Also added development NuGet feed to readme along with some other tweaks

* Project fixes (#35)

* fixed paths to NuGet packages folder; always relative to the .sln file

* converted samples solution file to VS 2017 and fixed "Deploy" flag for Android app

* ignore Android Resource designer generated files

# Conflicts:
#	.gitignore

* changes automatically applied by VS 2017 when opening iOS project file

* Added issue template

* fixes crash in Xamarin.Forms sample when user doesn't select file; also added example code in README file (#50)

* fixed picking files from the download folder; on newer devices the document ID may not be a number, but the real filename prefixed with "raw:" (#49)

* Updated dependencies

* Revert "Fixed Path" (#65)



* Revert "Fixed Path (#54)"

* when opening files with the sample app, ignore if filename extension is uppercase or lowercase

* removed unused method DidPickDocumentPicker() in iOS implementation

* added troubleshooting chapter to readme with common errors and their solutions

* updated sample projects to use PackageReference to reference NuGet packages

* removed obsolete project property AndroidUseLatestPlatformSdk and set target framework to Android 9.0 (API 28)

* updated Plugin.FilePicker.UWP to use PackageReference

* removed obsolete property AndroidUseLatestPlatformSdk and target Android 9.0, in Plugin.FilePicker.Android project

* updated sample projects to use Xamarin.Forms 3.3.0 NuGet package

* updated UWP project to latest stable UWP NuGet package

* fixed Android sample project by re-adding Xamarin.Forms NuGet package

* added UWP sample project

* find correct view controller to present document picker, by finding currently presented view controller

* Android: return from task with Exception that was thrown during file picking

before that, the caller only got a null FileData object without knowing what happened

* Android: also pass exception to task when setting up picking

* iOS: pass exceptions in DocumentPicker handler to picker task

* renamed Forms project folder to a shorter name and renamed the only page to MainPage

* added try-catch to call to PickFile() in order to display exceptions from picking

* delete Resource.designer.cs file from repository that is being regenerated by the compiler

* converted Xamarin.Forms sample project to use Project Sdk style .csproj proect file

* added second button to samples to pick image files

* added check if Android permission was granted

* fix android mime types implementation (#85)

(cherry picked from commit 04a52929bd8757d4d99315baca8c18348bc1640d)

* added explanation for requesting permissions on Android (#89)

* fixed exception when trying to pick a downloaded file; the Android DownloadManager won't return an actual file path; downloaded files can only be resolved using ContentResolver (#86)

* added solution folders to organize projects

* added UTType.Image file types value for picking on iOS

* Forms sample project can use .NET Standard 1.0; no need for version 2.0, which might not be installed

* added README.md for samples folder

* added Plugin.Permissions NuGet package to sample project, in order to check for permissions

* added checking Storage permission when on Android device

* iOS: simplified getting filename from pathname

* iOS: fixed getting pathname from FileUrl (fix of PR #54 that was reverted in PR #65); tested on iOS 11 device

* added documentation about FileData class to README