hmlgrep: implement --ignore-case
amlgrep: fix wrongly printing filename w/o -c option
Make --timestamp consistent for all of {a,h,py}mlgrep

and other minor fix like
- rename pmlgrep to pymlgrep
- fix amgrep newline handling
- deprecated amlgrep's --ors option because it can't be made consistent
  with oldRT behavior (oldRT used to print separator on top of a record,
  but ORS is on the bottom.)
amlgrep: make --dump option (xargs)compatible with MacOSX
test and minor fixes

Test script (runtest.sh) and test data in ./test directory.
Minor fixes to make all outputs equal
* hmlgrep - don't output extra newline for a match for topmost record
* amlgrep - newline handling of RT/oldRT
* pymlgrep - implemented --ignore-case option

Note that amlgrep's code is (wrongly) assuming record-separator takes
one whole line but actually it doesn't always -- result will be extra
or too few newlines
hmlgrep: use Text.Regex.PCRE instead of regex-compat
Merge branch 'master' of github.com:ryo1kato/mlr-grep

This is to consolidate pushed change with that of modified by --amend locally.

Conflicts:
	hmlgrep.hs