tests/test-encode.out

Fix hg push and hg push -r sometimes creating new heads without --force.
Fixing issue179.

The algorithm checks if there not more new heads on the remote side than heads
which become non-heads due to getting children.

Pushing this repo:
    m
   /\
3 3a|
|/  /
2 2a
|/
1

to a repo only having 1, 2 and 3 didn't abort requiring --force before.

Added test cases for this and some doc strings for used methods.

%% no changes
%% no changes
%% uncompressed contents in repo
this is a test
%% uncompress our working dir copy
this is a test
%% uncompress our new working dir copy
this is a test