(PPM) Use custom TIFF reader for loading cell map

[csparker247]

This overhauls TIFFIO.hpp to fix some bugs and add new features:

• Added tiffio::ReadTIFF which can read single image, 8, 16, and 32bpc TIFF files with various pixel types.
• Added TIFFIO unit tests
• tiffio::WriteTIFF automatically write TIFFs > 4GB as BigTIFF.
• tiffio::WriteTIFF better handles obscure, unsupported color conversions (e.g. CV_8SC3 and CV_8SC4 are not supported by cv::cvtColor)
• (PerPixelMap) Use tiffio::ReadTIFF for loading the cell map (fixes [Bug] PPM error when loading cell map > 1GB #42)
• (PerPixelMap) Better error handling for mask and cell map loading
• (PPM Tests) Test mask and cell map serialization

[csparker247]

For posterity, here's the code I used to test BigTIFF support. It's not a unit test because I don't want to write 4GB files in the unit tests:

#include <limits>
#include <random>
#include <iostream>

#include "vc/core/io/TIFFIO.hpp"
#include "vc/core/io/ImageIO.hpp"

using namespace volcart;

auto main() -> int
{
    using ElemT = std::uint16_t;
    auto low = std::numeric_limits<ElemT>::min();
    auto high = std::numeric_limits<ElemT>::max();
    static std::uniform_int_distribution<ElemT> dist(low, high);
    static std::default_random_engine gen;

    std::cout << "Creating big random image...\n";
    cv::Mat bigImg(50000, 50000, CV_16UC1);
    std::generate(bigImg.begin<ElemT>(), bigImg.end<ElemT>(), []() { return dist(gen); });
    std::cout << "Writing image...\n";
    tiffio::WriteTIFF("big_image.tif", bigImg, tiffio::Compression::NONE);

    std::cout << "OpenCV: Reading image...\n";
    try {
        const cv::Mat img = volcart::ReadImage("big_image.tif");
        std::cout << img.rows << "x" << img.cols << "\n";
        std::cout << cv::typeToString(img.type()) << "\n";
    } catch (const std::exception& e) {
        std::cout << "OpenCV: Failed to read: " << e.what() << "\n";
    }

    std::cout << "TIFFIO: Reading image...\n";
    try {
        const cv::Mat img = tiffio::ReadTIFF("big_image.tif");
        std::cout << img.rows << "x" << img.cols << "\n";
        std::cout << cv::typeToString(img.type()) << "\n";
    } catch (const std::exception& e) {
        std::cout << "TIFFIO: Failed to read: " << e.what() << "\n";
    }
}