Moved logcat.vim in its syntax subdir

The logcat.vim file is meant to be stored in a ~/.vim/syntax/logcat.vim
subdir. Creating the syntax subdir makes the installation much easier.
Plus, it simplifies the use of the pathogen plugin.
Extensive modifications on logcat.vim

New matches, regions and keywords definitions.
Use of the full 256 color palette.
O joy, an explosion of colours ! \o/
Adding a ftdetect subdir

This subdir contains rules for logcat files autodetection.
The detection is based on extension (.lc or .logcat) or a regexp (for
details, take a look at the script).
Documentation matching the preceding changes

Who doesn't need moar doc ?