Add hledger and its missing dependencies

hledger is a computer program for easily tracking money, time, or
other commodities, inspired by and compatible with ledger.

Add:
    mtlparse
    regexpr
    shakespeare
    shakespeare-text
    haskell-lexer
    pretty-show
    hledger-lib
    hledger

Signed-off-by: Fabien Dubosson <fabien.dubosson@gmail.com>