histedit: mark as a first party extension

histedit: remove use of reduce() builtin spotted by check-code

test-histedit-edit: improve coverage of histedit code

histedit: fix most check-code violations

histedit tests: fix check-code problems

histedit: new extension for interactive history editing

exewrapper: use generic term script The exewrapper doesn't know anything so far about what the script is or does.

Makefile: add build_hgexe -i for local

setup: compile hg.exe This implements a new command $ python setup.py build_hgexe -i which places the hg.exe in the root of the source tree.

test-commit-amend: adapt for Windows after fba17a64fa49