Ignore conflict markers in ConvertUCD

[eggrobin]

We might need to do that for other parsers at some point; this is the only one that posed problems when merging #442 and #441.

Note that after merging and before running MakeUnicodeFiles, the Derived files need to be reset to a non-conflicting state, otherwise the ranges either side of the conflict markers overlap. UnicodeData is obviously immune to that.

This will probably be a problem for some source files eventually (LineBreak or Script), so I am leaving #419 open; we’ll cross that bridge when we get to it.

[eggrobin]

Tested with five of the pipeline PRs:
The last four commits on https://github.com/eggrobin/unicodetools/commits/deconfliction-test are all mindlessly produced by:

1. merge;
2. checkout the Derived* and extracted/* at HEAD;
3. regenerate the UCD;
4. commit.

[eggrobin]

mindlessly

A little bit too mindlessly even, since of course this process retains all conflict markers in UnicodeData.txt!

[eggrobin]

Alright, trying again now that UnicodeData is regenerated: the last 5 commits of https://github.com/eggrobin/unicodetools/commits/deconfliction-test were produced by:

foreach ($branch in @('170-C7', '170-C15', '170-C17', '172-C3', '171-C13')) {
  git fetch origin;
  git merge origin/$branch;
  git checkout HEAD unicodetools/data/ucd/dev/Derived*;
  git checkout HEAD unicodetools/data/ucd/dev/extracted/*;
  git checkout HEAD unicodetools/data/ucd/dev/auxiliary/*;
  rm .\Generated\* -recurse -force;
  mvn compile exec:java '-Dexec.mainClass="org.unicode.text.UCD.Main"'  '-Dexec.args="build MakeUnicodeFiles"' -am -pl unicodetools  "-DCLDR_DIR=..\cldr\"  "-DUNICODETOOLS_GEN_DIR=Generated"  "-DUNICODETOOLS_REPO_DIR=.";
  cp .\Generated\UCD\15.1.0\* .\unicodetools\data\ucd\dev -recurse -force;
  rm unicodetools\data\ucd\dev\zzz-unchanged-*;
  rm unicodetools\data\ucd\dev\*\zzz-unchanged-*;
  rm .\unicodetools\data\ucd\dev\extra\*;
  rm .\unicodetools\data\ucd\dev\cldr\*;
  git commit -am "merge $branch";
}

[markusicu]

lgtm -- nice! looking forward to see it in live action :-)