- parallel reading when writing tiffs

- add version argument to distinguish between versions of the .iss-pt file
- update readme

README.md

@@ -1,2 +1,29 @@
 # issfile
-LIbrary for opening ISS (iss.com) files and conversion to tiff.
+Library for opening [ISS](https://iss.com) files and their conversion to tiff.
+
+## Installation
+
+    pip install git+https://github.com/wimpomp/issfile.git
+
+## Converting .iss-pt files to .tiff files
+
+    iss2tiff --help
+
+    iss2tiff file.iss-pt
+
+this will create file.tiff and file.carpet.tiff containing images and carpets respectively.
+Metadata is also saved in the tiffs in the description tag.
+
+## Use as a library
+
+    from matplotlib import pyplot as plt
+    from issfile import IssFile
+
+    with IssFile(file) as iss:
+        image = iss.get_image(c=1, t=5)
+        carpet = iss.get_carpet(c=1, t=5)
+    
+        plt.figure()
+        plt.imshow(image)
+        plt.figure()
+        plt.plot(carpet.sum(1))