[Freeciv-Dev] (PR#9147) researchcost proposal

["Per Inge Mathisen" <per@xxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=9147 >

I propose that
 - doubling researchcost after a given date is made a ruleset option,
defaulting to off (now it doubles at year 1)
 - a new researchcost option is added, which is researchcost * no. tech
dependencies * sqrt(no. tech dependencies), and this is made default.
 - researchcost is set to 5 (now 10)

The resulting tech costs becomes:
deps    cost
1       5
2       14
3       26
4       40
5       56
6       73
7       93
8       113
9       135
10      158
11      182
12      208
13      234
14      262
15      290
16      320
17      350
18      382
19      414
20      447
21      481
22      516
23      552
24      588
25      625
26      663
27      701
28      741

Currently, research cost for your 28th tech is 280 before 1AD and 560
after 1AD.

The above will slow down research in a more graceful way that the doubling
of researchcost after 1AD, and also slow it down a bit in general.

PS Note that since I propose that we count number of dependencies of a
tech and not number of techs ever researched, similar to
tech_cost_style=1, the costs do not increase as much as the above would
seem to indicate. Here is a list to show the difference between the
tech_cost_style=0 (default rules) and tech_cost_style=1 for some late
techs (full list available on request), current cost in parenthesis:

calculating tech cost for Advanced Flight to 560 (would be 670), prereqs 56
calculating tech cost for Rocketry to 580 (would be 680), prereqs 58
calculating tech cost for Combined Arms to 590 (would be 690), prereqs 59
calculating tech cost for Polytheism to 30 (would be 700), prereqs 3
calculating tech cost for Monotheism to 100 (would be 710), prereqs 10
calculating tech cost for Theology to 140 (would be 720), prereqs 14
calculating tech cost for Atomic Theory to 180 (would be 730), prereqs 18
calculating tech cost for Espionage to 340 (would be 740), prereqs 34
calculating tech cost for Nuclear Fission to 490 (would be 750), prereqs 49
calculating tech cost for Nuclear Power to 510 (would be 760), prereqs 51
calculating tech cost for Space Flight to 630 (would be 770), prereqs 63
calculating tech cost for Genetic Engineering to 360 (would be 560), prereqs 36
calculating tech cost for Laser to 520 (would be 780), prereqs 52
calculating tech cost for Refrigeration to 330 (would be 790), prereqs 33
calculating tech cost for Plastics to 640 (would be 800), prereqs 64
calculating tech cost for Superconductors to 530 (would be 810), prereqs 53
calculating tech cost for Fusion Power to 540 (would be 820), prereqs 54
calculating tech cost for Stealth to 660 (would be 830), prereqs 66

  - Per