run-test.py: greatly increase the priority of 'check-code' tests As check-code is actually quite long to run for its file size, this prevent them to be scheduled too late during the test run. This reduces my typical test run from 107 seconds to 90 seconds

run-tests: allow different extra weight for slow tests The 'test-check-code-hg.t' file is not big enough to be prioritized properly. As a result my tests run often spend about 15 seconds running only it at the end of its tests run. We make the "slow" mechanism a bit smarter to adjust the extra weight of each category independently in a future patch.

ignore: refactor syntax concatenation This refactors the syntax+rule concatenation logic to be more separated. It determines the syntax and the rule separately and then puts them back together. This will help in a later patch when we want to process just the rule before it gets concatenated.

ignore: refactor file read into a function This refactors the ignore file reading code into a function so that in a future patch we can make it recursive.

import-checker: loop to get list of locally defined modules at first This is a preparation for subsequent patches, which expect that all locally defined (= mercurial specific) modules are already known before examinations. Looping twice for specified modules is a little redundant, but reasonable cost for improvement in subsequent patches.

import-checker: add xargs like mode Before this patch, "import-check.py" is invoked via "xargs" in "test-module-imports.t", but it doesn't ensure that "import-checker.py" is certainly invoked with all mercurial specific files at once. "xargs" may invoke specified command multiple times with part of arguments given from stdin: according to "xargs(1)" man page, this dividing arguments is system-dependent. This patch adds "xargs" like mode to "import-checker.py". This can ensure that "import-checker.py" is certainly invoked with all mercurial specific files at once in "test-module-imports.t". This is assumed by subsequent patches.