Merge pull request #2248 from hafriedlander/fix/flush_30

FIX: Have ParameterConfirmationToken work regardless of include path
Merge pull request #2255 from hafriedlander/fix/flush_30

Split Core.php into Constants.php and Core.php and adjust main.php startup
Merge pull request #2257 from hafriedlander/fix/flush_30

FIX Nice errors and allows flush on module removal
Merge pull request #2285 from hafriedlander/fix/flush_30

FIX Flush on memory exhaustion and when headers sent
Translations: Switch to Transifex format

- Based on new (last) translation download from getlocalization.com
- Removed untranslated strings. Getlocalization started including those at some point
which is highly annoying, unnecessary and breaks the new transfix system,
since it'll mark all of the english strings as actual translations
- Avoid dots in entities. It confuses the Transifex YML parser
- Removed some locales unknown to Transifex which didn't have any translations anyway
- Removed "lolcat" locale, uses custom notation (en@lolcal)
  which SilverStripe's i18n system can't handle
  (needs mapping from SS naming to Zend naming)
- Renamed "Te Reo/Maori" locale from "mi_NZ" to "mi" (Transifex/CLDR notation)
- Namespaced all entities used in templates (deprecated usage)
- Converted dots to underscores where template filenames are used for namespaces,
since Transifex YML parsing handles them as separate YML keys otherwise
- Removed whitespace in entity names, SilverStripe i18n can't handle it
- Only allow selection of locales registered through i18n::$all_locales to avoid
  issues with unknown locales in Zend's CLDR database
Merge pull request #2291 from chillu/pulls/transifex-3.0

Translations: Switch to Transifex format (3.0)
Fixed "session started" error on install.php
Create folder if required in dev/generatesecuretoken
Added 3.0 changelog
Added 3.0.6-rc1 changelog
Fixed issue with inconsistent use of punctuation and wording of Tutorial 5 summary
Merge pull request #2313 from jbridson/patch-1

Fixed issue with inconsistent use of punctuation and wording of Tutorial...
Fixed Grammatical errors and issues where sentences didn't make sense.
Merge pull request #2315 from jbridson/patch-2

Fixed Grammatical errors and issues where sentences didn't make sense.
FIX Double slashes in ParameterConfirmationToken