metomi/rose#251: improve fcm_make task utils.

Allow configuration as a Rose app.
fcm_make2* task will automatically use fcm_make* task's Rose app.
Remove support for ROSE_TASK_PRE_SCRIPT.
metomi/rose#251: document behaviour changes.
doc: fix typo.
metomi/rose#251: fcm_make task utils logic fixes.
metomi/rose#251: fix doc typos.
Merge branch 'master' into 251.task-utils.fcm-make
Merge branch '251.task-utils.fcm-make' of github.com:matthewrmshin/rose into 251.task-utils.fcm-make
metomi/rose#251: fix typo.
Merge pull request #299 from matthewrmshin/251.task-utils.fcm-make

rose task-run: built-in fcm_make task util: improve. Closes #251