(svn r7331) - Codechange: Rename all memory pool macro's and types to "old pool", so the new pool implementation can be committed alongside it.
- Codechange: Rename pool.[ch] to oldpool.[ch].

(svn r6155) -Codechange: split Destroy routine from SpriteGroupPoolCleanBlock
Last change is to prepare for new pool system.

(svn r5975) -Cleanup: use ORIGINAL_BASE_YEAR & ORIGINAL_MAX_YEAR where the functions really depend on the original date format.
-Cleanup: use DAYS_TILL_ORIGINAL_BASE_YEAR where the date variables are in the old date format and conversions are needed.
-Cleanup: replace one (forgotten) instance of uint16 with Date.

(svn r5926) -Codechange: make _cur_year contain the full year, instead of the offset since 1920
-Codechange: store all year related variables that are _not_ stored in a savegame/transported over the network in the same format as _cur_year

(svn r5887) -Cleanup: move date related functions, defines and variables to date.[ch]
-Cleanup: fix whitespace related coding style issues in date.[ch]
-Cleanup: make original comments doxygen compatible and remove/change outdated comments

(svn r5136) Fix various style bugs:
- Trailing whitespace
- Trailing empty lines
- Missing newline at EOF
- Missing svn:eol-style native

(svn r4486) - NewGRF: Create and use a memory pool to manage sprite groups. This
reduces the amount of house keeping we do and the chance of memory
leaks.