#55 add .jacl files to tcl file type

[Andriy Gapon]

JACL is TCL implementation written in Java. Some Jacl
flavors have certain differences from some TCL flavors,
but in general, the syntax and essentail operators and
functions are the same.
It is customarily to use .jacl extension with for
scripts written in Jacl.
Please add this extension to tcl filetype in filetype.vim.