Fix for issue #261, Access to UIImagePickerController Object

[brt-manishp]

In "showCamera()" there is a local variable called "picker" which I need it access to configure image picker for various use case. So I made a public optional variable of UIImagePickerController in "TLPhotosPickerConfigure" and used it in "showCamera()" with null check

Changes made are as follows in file named TLPhotosPickerViewController.swift

public struct TLPhotosPickerConfigure {
    .........
    public var uiimagePickerController: UIImagePickerController?  //line 99
    .........
}

// MARK: - Camera Picker  
extension TLPhotosPickerViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
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private func showCamera() {  //line 595
    guard !maxCheck() else { return }
    if let picker = self.configure.uiimagePickerController {
        self.present(picker, animated: true, completion: nil)
    }else {
        let picker = UIImagePickerController()
        picker.sourceType = .camera
        picker.mediaTypes = [kUTTypeImage as String]
        if self.configure.allowedVideoRecording {
            picker.mediaTypes.append(kUTTypeMovie as String)
            picker.videoQuality = self.configure.recordingVideoQuality
            if let duration = self.configure.maxVideoDuration {
                picker.videoMaximumDuration = duration
            }
        }
        picker.allowsEditing = false
        picker.delegate = self
        self.present(picker, animated: true, completion: nil)
    }
}
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}