Remove unused lib/core/image_science.rb
Remove unused lib/core/image_science.rb

It was added in ca0be4e6a016b866ce80bd3f56be7da78f4b1d8a for fallback option for RMagick.
But suddenly removed in 838682ea82e7c09192ca6ac4465e004c5bb784ff IDKW.
Currently rbpdf doesn't ship this file.

```
% gem unpack rbpdf --target=/tmp/rbpdf
Unpacked gem: '/tmp/rbpdf/rbpdf-1.19.8'
% tree /tmp/rbpdf/rbpdf-1.19.8
/tmp/rbpdf/rbpdf-1.19.8
├── CHANGELOG
├── Gemfile
├── LICENSE.TXT
├── MIT-LICENSE
├── README.md
├── Rakefile
├── lib
│   ├── core
│   │   └── rmagick.rb
│   ├── htmlcolors.rb
│   ├── rbpdf
│   │   └── version.rb
│   ├── rbpdf.rb
│   └── unicode_data.rb
├── logo_example.png
├── rbpdf.gemspec
├── test
│   ├── err_font1.rb
│   ├── err_font2.rb
│   ├── logo_rbpdf_8bit .png
│   ├── logo_rbpdf_8bit+ .png
│   ├── logo_rbpdf_8bit.gif
│   ├── logo_rbpdf_8bit.jpg
│   ├── logo_rbpdf_8bit.png
│   ├── logo_rbpdf_8bit_alpha.gif
│   ├── logo_rbpdf_mono_gray.jpg
│   ├── logo_rbpdf_mono_gray.png
│   ├── logo_rbpdf_mono_rgb.jpg
│   ├── logo_rbpdf_mono_rgb.png
│   ├── png_test_alpha.png
│   ├── png_test_msk_alpha.png
│   ├── png_test_non_alpha.png
│   ├── rbpdf_bidi_test.rb
│   ├── rbpdf_bookmark_test.rb
│   ├── rbpdf_cell_test.rb
│   ├── rbpdf_content_test.rb
│   ├── rbpdf_css_test.rb
│   ├── rbpdf_dom_test.rb
│   ├── rbpdf_examples_test.rb
│   ├── rbpdf_font_func_test.rb
│   ├── rbpdf_font_style_test.rb
│   ├── rbpdf_font_test.rb
│   ├── rbpdf_format_test.rb
│   ├── rbpdf_func_test.rb
│   ├── rbpdf_html_anchor_test.rb
│   ├── rbpdf_html_func_test.rb
│   ├── rbpdf_html_test.rb
│   ├── rbpdf_htmlcell_test.rb
│   ├── rbpdf_http_test.rb
│   ├── rbpdf_image_rmagick_test.rb
│   ├── rbpdf_image_test.rb
│   ├── rbpdf_test.rb
│   ├── rbpdf_transaction_test.rb
│   ├── rbpdf_viewerpreferences_test.rb
│   ├── rbpdf_write_test.rb
│   └── test_helper.rb
├── test_unicode.rbpdf
└── utf8test.txt

4 directories, 54 files
```

planio-gmbh/rbpdf,planio-gmbh/rbpdf