Spell check, re-format and re-phrase the TODO list.

TODO.md

@@ -1,3 +1,22 @@
+# The TODO list for mboxgrep
+
+## Behavior
+
+- [x] enable removing duplicate messages w/ MD5 checksums
+- [ ] add checking for conflicting command-line options
+- [ ] support for deletion of messages after being matched and displayed
+
+## File formats, encodings and standards
+
+- [ ] MIME support
+- [ ] support for GnuPG
+- [x] support for compressed mbox folders
+- [x] support for bzip2 compression
+- [ ] support for XZ-format compression
+- [ ] support for mail folder conversion
+
+## Miscellaneous
+
 - [x] ignore .overview when grepping Gnus folders
 - [x] inverted matching
 - [x] recursive search through directories
@@ -5,19 +24,10 @@
 - [x] write Texinfo documentation
 - [x] writing selected messages to a new folder
 - [x] deleting selected messages
-- [ ] support for config files
-- [x] support for reading messages from stdin
-- [x] support for compressed mbox folders
+- [ ] configuration files
+- [x] reading messages from standard input
 - [ ] make use of lockfile library
 - [ ] make use of Solaris' maillock library
 - [x] provide possibility to use flock() instead of fcntl()
 - [x] allow run-time selection of file locking method
 - [ ] provide national language support with gettext()
-- [ ] MIME support
-- [x] enable removing duplicate messages w/ MD5 checksums
-- [ ] add checking for conflicting command-line options
-- [ ] support for GnuPG
-- [x] support for bzip2 compression
-- [ ] support for XZ-format compression
-- [ ] support for mail folder conversion
-- [ ] support for deletion of messages after being matched and displayed