fix for 'store absolute paths internally'

`parent_path` was called on unprocessed path
so neither `resolve_path` nor `filesystem::absolute` had any effect.
remove superfluous 'break'
add unit tests for amount_t→floor/ceil
fix bug 788: behaviour of source_context for '-f -'

`session_t::read_data` did not set context.pathname to `/dev/stdin`
for the special case `-f -`. I chose to adjust `source_context` too
as there is no sensible context if no file name is provided.
fix bug 748: option aliases not recognized
Fixed ledger-add-entry

copied ledger-iterate-entries, ledger-set-year and ledger-set-month
from the old ledger.el.  Changed ledger-add-entry to use
ledger-exec-ledger vice the old ledger-run-ledger.
Merge pull request #122 from enderw88/Lisp-fixes

Fix ledger-add-entry