Add custom image dir option

Author: Belval

Dockerfile

@@ -36,4 +36,5 @@ RUN git clone https://github.com/python-pillow/Pillow.git \
  && python3 setup.py build_ext --enable-freetype install
 
 RUN python3 setup.py install
+RUN pip3 install -r requirements-hw.txt
 

MANIFEST.in

@@ -2,6 +2,6 @@ include README.md
 include LICENSE
 include trdg/fonts/latin/*
 include trdg/fonts/cn/*
-include trdg/pictures/*
+include trdg/images/*
 include trdg/dicts/*
 include trdg/texts/*

README.md

@@ -119,14 +119,14 @@ But scanned document usually aren't that clear are they? Add `-bl` and `-rbl` to
 
 ### Background
 
-Maybe you want another background? Add `-b` to define one of the three available backgrounds: gaussian noise (0), plain white (1), quasicrystal (2) or picture (3).
+Maybe you want another background? Add `-b` to define one of the three available backgrounds: gaussian noise (0), plain white (1), quasicrystal (2) or image (3).
 
 ![15](samples/15.jpg "0")
 ![16](samples/16.jpg "1")
 ![17](samples/17.jpg "2")
 ![23](samples/23.jpg "3")
 
-When using picture background (3). A picture from the pictures/ folder will be randomly selected and the text will be written on it.
+When using image background (3). A image from the images/ folder will be randomly selected and the text will be written on it.
 
 ### Handwritten